File multipage with variable page format

You could use the adjustwidth environment from the changepage package.

...
usepackage{changepage}
...
begin{adjustwith}{}{-8em}
wider text
end{adjustwidth}
...

The two arguments lengths are added to the left and right margins respectively; positive value(s) decrease the local textwidth and negative value(s) increases it.

I'm afraid you have to come up with your own solution for your problem.

The standalone style in combination with TikZ will produce a single PDF-page for each tikzpicture having the size of the (TikZ-)picture. Maybe this could be a start for you. You could include your figures using node and includegraphics.

This code will generate a PDF with three pages (just filled with a coloured rectangle).

documentclass[tikz,crop=true,border=-3pt]{standalone}
begin{document}

begin{tikzpicture}
fill[red] (0,0) rectangle (2,3);
end{tikzpicture}

begin{tikzpicture}
fill[green] (0,0) rectangle (5,5);
end{tikzpicture}

begin{tikzpicture}
fill[blue] (0,0) rectangle (3,1);
end{tikzpicture}

end{document}