Adding arrows outside of plot area and aligning plots

I am trying to re-create this plot:

This is a follow on post to one I made previously here. I am getting closer but I want to know how to add the arrows "D1", "Box 2" "D2" etc. to the plot.

Additionally, I cannot see to "fix" the 3rd plots red coordinate background colour.

Current attempt gives me:

Tex:

documentclass[]{article}
%%%%%%% Packages to force the plots to work %%%%
usepackage{tikz}
usepackage{pgfplots}
usepgfplotslibrary{fillbetween}
usetikzlibrary{plotmarks}

definecolor{babyblue}{rgb}{0.54, 0.81, 0.94}
definecolor{bubblegum}{rgb}{0.99, 0.76, 0.8}
begin{document}

%%%%%%%%%%%%%%% basic scatter plot %%%%%%%%%%%%%%%%

begin{figure}

% plot 1: base plot
begin{tikzpicture}[scale=0.40]
  pgfplotsset{
      scale only axis,
  }
  begin{axis}[
    %xlabel=$A$,
    %ylabel=$B$,
    ticks=none,
  ]

    addplot[only marks, mark=+, mark size=8pt, thin, color = blue]
    coordinates{ % + data
      (0.05,0.50)
      (0.10,0.15)
      (0.30,0.85)
      (0.45, 0.95)
      (0.60, 0.75)
    }; %label{plot_one}
    addplot[only marks, mark=-, mark size=8pt, thin, color = red]
    coordinates{ % + data
      (0.20,0.05)
      (0.25,0.60)
      (0.55,0.40)
      (0.90, 0.85)
      (0.90, 0.15)
    };
    draw (axis cs:0.15, -0.1)--(axis cs:0.15, 1.1);
    path[name path = begin_left_shade_path] (axis cs:0.15, 1.0) -- (axis cs:0.0, 1.0);
    path[name path = end_left_shade_path] (axis cs:0.0, 0.0) -- (axis cs:0.15, 0.0);
    addplot [babyblue] fill between[of = begin_left_shade_path and end_left_shade_path, soft clip = {domain=0.0:1.0}];
    % plot 1 legend entry
    %addlegendimage{/pgfplots/refstyle=plot_one}
   %addlegendentry{D 1}
  end{axis}
end{tikzpicture}
hspace{0.5cm}%
% plot 2: adjusted plot
begin{tikzpicture}[scale=0.40]
  pgfplotsset{
      scale only axis,
  }
  begin{axis}[
    %xlabel=$A$,
    %ylabel=$B$,
    ticks=none,
  ]
    addplot[only marks, mark=+, mark size=6pt, thin, color = blue]
    coordinates{ % + data
      (0.05,0.50)
      (0.10,0.15)
      };
    addplot[only marks, mark=+, mark size=10pt, thin, color = blue]
    coordinates{ % + data
      (0.30,0.85)
      (0.45, 0.95)
      (0.60, 0.75)
    }; %label{plot_one}
    addplot[only marks, mark=-, mark size=6pt, thin, color = red]
    coordinates{ % + data
      (0.20,0.05)
      (0.25,0.60)
      (0.55,0.40)
      (0.90, 0.85)
      (0.90, 0.15)
    };
    draw (axis cs:0.80, -0.1)--(axis cs:0.80, 1.1);
    path[name path = begin_left_shade_path] (axis cs:0.80, 1.0) -- (axis cs:0.0, 1.0);
    path[name path = end_left_shade_path] (axis cs:0.0, 0.0) -- (axis cs:0.80, 0.0);
    addplot [babyblue] fill between[of = begin_left_shade_path and end_left_shade_path, soft clip = {domain=0.0:1.0}];
    
    path[name path = begin_left_shade_path_2] (axis cs:1.0, 1.0) -- (axis cs:0.80, 1.0);
    path[name path = end_left_shade_path_2] (axis cs:1.0, 0.0) -- (axis cs:0.80, 0.0);
    addplot [bubblegum] fill between[of = begin_left_shade_path_2 and end_left_shade_path_2, soft clip = {domain=0.0:1.0}];
    % plot 1 legend entry
    %addlegendimage{/pgfplots/refstyle=plot_one}
   %addlegendentry{D 2}
  end{axis}
end{tikzpicture}
hspace{0.5cm}%
% plot 3: adjusted plot
begin{tikzpicture}[scale=0.40]
  pgfplotsset{
      scale only axis,
  }
  begin{axis}[
    %xlabel=$A$,
    %ylabel=$B$,
    ticks=none,
  ]
    addplot[only marks, mark=oplus, mark size=6pt, thin, color = blue]
    coordinates{ % + data
      (0.05,0.50)              % Add circle around here
      (0.10,0.15)              % Add circle around here
      };
    addplot[only marks, mark=+, mark size=8pt, thin, color = blue]
    coordinates{ % + data
      (0.30,0.85)
      (0.45, 0.95)
      (0.60, 0.75)
    }; %label{plot_one}
    addplot[only marks, mark=-, mark size=10pt, thin, color = red]
    coordinates{ % - data
      (0.20,0.05)
      (0.25,0.60)
      (0.55,0.40)
      };
      addplot[only marks, mark=otimes, mark size=4pt, thin, color = red]
    coordinates{ % - data
      (0.90, 0.85)             % Add circle around here
      (0.90, 0.15)
    };
    addplot[only marks, mark=ominus, mark size=4pt, thin, color = red]
    coordinates{ % - data
          (0.90, 0.85)             % Add circle around here
    };
    draw (axis cs:-0.1, 0.70)--(axis cs:1.1, 0.70);
    
    path[name path = begin_left_shade_path_1] (axis cs:0.0, 0.7) -- (axis cs:1.0, 0.7);
    path[name path = end_left_shade_path_1] (axis cs:0.0, 0.0) -- (axis cs:1.0, 0.0);
    addplot [bubblegum] fill between[of = begin_left_shade_path_1 and end_left_shade_path_2, soft clip = {domain=0.0:1.0}];
    
    path[name path = begin_left_shade_path_2] (axis cs:0.0, 1.0) -- (axis cs:1.0, 1.0);
    path[name path = end_left_shade_path_2] (axis cs:0.0, 0.70) -- (axis cs:1.0, 0.70);
    addplot [babyblue] fill between[of = begin_left_shade_path_2 and end_left_shade_path_2, soft clip = {domain=0.0:1.0}];

    % plot 1 legend entry
    %addlegendimage{/pgfplots/refstyle=plot_one}
   %addlegendentry{D 3}
  end{axis}
end{tikzpicture}
end{figure}

% plot 4: Combined plot
begin{tikzpicture}[scale=0.40]
  pgfplotsset{
      scale only axis,
  }
  begin{axis}[
    %xlabel=$A$,
    %ylabel=$B$,
    ticks=none,
  ]

    addplot[only marks, mark=+, mark size=8pt, thin, color = blue]
    coordinates{ % + data
      (0.05,0.50)
      (0.10,0.15)
      (0.30,0.85)
      (0.45, 0.95)
      (0.60, 0.75)
    }; %label{plot_one}
    addplot[only marks, mark=-, mark size=8pt, thin, color = red]
    coordinates{ % + data
      (0.20,0.05)
      (0.25,0.60)
      (0.55,0.40)
      (0.90, 0.85)
      (0.90, 0.15)
    };
    draw (axis cs:0.15, -0.1)--(axis cs:0.15, 1.1);
    path[name path = begin_left_shade_path] (axis cs:0.15, 1.0) -- (axis cs:0.0, 1.0);
    path[name path = end_left_shade_path] (axis cs:0.0, 0.0) -- (axis cs:0.15, 0.0);
    addplot [babyblue] fill between[of = begin_left_shade_path and end_left_shade_path, soft clip = {domain=0.0:1.0}];    
    
    
    draw (axis cs:0.80, -0.1)--(axis cs:0.80, 1.1);
    path[name path = begin_left_shade_path_2] (axis cs:1.0, 1.0) -- (axis cs:0.80, 1.0);
    path[name path = end_left_shade_path_2] (axis cs:1.0, 0.0) -- (axis cs:0.80, 0.0);
    addplot [bubblegum] fill between[of = begin_left_shade_path_2 and end_left_shade_path_2, soft clip = {domain=0.0:1.0}];
    
    
    draw (axis cs:-0.1, 0.70)--(axis cs:1.1, 0.70);
    
    
    
    % plot 1 legend entry
    %addlegendimage{/pgfplots/refstyle=plot_one}
   %addlegendentry{D 1}
  end{axis}
end{tikzpicture}

end{document}

documentclass[tikz]{standalone}
% Matthias Arras, 2020
usetikzlibrary{calc,decorations.pathreplacing}

% dimension definitions
pgfmathsetmacro{squaresize}{2} % size of the rectangle
pgfmathsetmacro{horposONE}{25} %angle where line intercepts rectangle from center
pgfmathsetmacro{horposTWO}{-25}
pgfmathsetmacro{vertposONE}{90-25}
pgfmathsetmacro{vertposTWO}{90+25}

%define standard colors for the squares
tikzset{
  rect0/.style=red!50,rect1/.style=red!50,rect2/.style=red!50,
  rect3/.style=red!50,rect4/.style=red!50,rect5/.style=red!50,rect6/.style=red!50,
  rect7/.style=red!50,rect8/.style=red!50
}
%prepare styles for the charge
tikzset{
  charge0/.style={},charge1/.style={},charge2/.style={},
  charge3/.style={},charge4/.style={},charge5/.style={},charge6/.style={},
  charge7/.style={},charge8/.style={},charge9/.style={},
}
%define 'flexible' square pic with 9 compartments and 4 lines
tikzset{
pics/rect/.style args={#1/#2/#3/#4}{
code={
node[minimum size=squaresize cm,name=rect]{};

%Locations on rectangle starting at 10 o'clock with A
coordinate (A) at (rect.{180-horposONE});
coordinate (B) at (rect.vertposTWO);
coordinate (C) at (rect.vertposONE);
coordinate (D) at (rect.horposONE);
coordinate (E) at (rect.horposTWO);
coordinate (F) at (rect.{360-vertposONE});
coordinate (G) at (rect.{360-vertposTWO});
coordinate (H) at (rect.{180-horposTWO});


%make fillings of rectangle
filldraw[rect0] (A)rectangle(B);
filldraw[rect1] (B)rectangle(C|-D);
filldraw[rect2] (C)rectangle(D);
filldraw[rect3] (A)rectangle(G|-H);
filldraw[rect4] (A-|B)rectangle(E-|F);
filldraw[rect5] (D-|C)rectangle(E);
filldraw[rect6] (H)rectangle(G);
filldraw[rect7] (F)rectangle(H-|G);
filldraw[rect8] (E)rectangle(F);

% make horizontal or vertical lines
draw[mylinestyle,draw=#1](A)--(D);
draw[mylinestyle,draw=#2](H)--(E);
draw[mylinestyle,draw=#3](B)--(G);
draw[mylinestyle,draw=#4](C)--(F);

% Put charges
node[blue,mycharge,charge0] at (-squaresize/2*0.85,-squaresize/2*0){$+$};
node[blue,mycharge,charge0] at (-squaresize/2*0.70,-squaresize/2*0.7){$+$};
node[red,mycharge,charge2] at (-squaresize/2*0.3,-squaresize/2*0.8){$-$};
node[red,mycharge,charge3] at (-squaresize/2*0.25,squaresize/2*0.2){$-$};
node[blue,mycharge,charge4] at (-squaresize/2*0.2,squaresize/2*0.8){$+$};
node[blue,mycharge,charge5] at (squaresize/2*0.1,squaresize/2*0.85){$+$};
node[red,mycharge,charge6] at (squaresize/2*0.15,-squaresize/2*0.3){$-$};
node[blue,mycharge,charge7] at (squaresize/2*0.25,squaresize/2*0.65){$+$};
node[red,mycharge,charge8] at (squaresize/2*0.8,squaresize/2*0.8){$-$};
node[red,mycharge,charge9] at (squaresize/2*0.8,-squaresize/2*0.8){$-$};

% draw outer rectangle
draw[mylinestyle,black](-squaresize/2,-squaresize/2)rectangle(squaresize/2,squaresize/2);


}}}

begin{document}
begin{tikzpicture}[
mylinestyle/.style={thick},
myarrowstyle/.style={latex-,thick,shorten <=2pt},
mycharge/.style={inner sep=-0.5pt,circle}
]
% use pic like so:
% pic[options]{rect={linecolorLINEa/linecolorLINEb/linecolorLINEc/linecolorLINEd}}; use linecolor=none if you dont want to draw a lines
% notable options for pic here are
% rect0-rect8, each can be used to define the color of the subsquare; 0 is left upper corner and goes in zigzag fashion to bottom right is 8. Per default all rect are red!50 color.
% charge0-charge9, can be used modify the style to draw=red or draw=blue option to draw a circle around the charge in the corresponding color.
% EXAMPLE
% pic[rect0./style={blue!50},charge0/.style={draw=blue}]{rect={black/none/none/none}};

% First Box
pic[local bounding box=BoxA,rect0/.style={blue!50},rect3/.style={blue!50},rect6/.style={blue!50}] at (0,0) {rect={none/none/black/none}};
draw[myarrowstyle](BoxA.west)--++(180:0.5cm)node[anchor=east]{Box 1};
draw[myarrowstyle](B)--++(45:0.5cm)node[anchor=south,font=footnotesize]{D1};
%Second Box
pic[local bounding box=BoxB,rect0/.style={blue!50},rect3/.style={blue!50},rect6/.style={blue!50},rect1/.style={blue!50},rect4/.style={blue!50},rect7/.style={blue!50}] at (squaresize*1.5,0) {rect={none/none/none/black}};
draw[myarrowstyle](BoxB.north)--++(90:0.5cm)node[anchor=south]{Box 2};
draw[myarrowstyle](C)--++(45:0.5cm)node[anchor=south,font=footnotesize]{D2};
%Third Box
pic[local bounding box=BoxC,rect0/.style={blue!50},rect1/.style={blue!50},rect2/.style={blue!50}] at (squaresize*2*1.5,0) {rect={black/none/none/none}};
draw[myarrowstyle](BoxC.east)--++(0:0.5cm)node[anchor=west]{Box 3};
draw[myarrowstyle](D)--++(45:0.5cm)node[anchor=south,font=footnotesize]{D3};
%Fourth Box
pic[local bounding box=BoxD,rect0/.style={blue!50},rect1/.style={blue!50},rect3/.style={blue!50},rect6/.style={blue!50},charge8/.style={draw=red}] at (squaresize*1.5,-squaresize*1.5) {rect={black/none/black/black}};
draw[myarrowstyle](BoxD.south)--++(-90:0.5cm)node[anchor=north]{Box 4};

% Brace
draw [decorate,decoration={brace,amplitude=20pt,mirror,raise=4pt},yshift=0pt]
(BoxA.south) -- (BoxC.south);

end{tikzpicture}
end{document}