Get a table of org-mode file from elisp to be passed to R

Here's an example Org file (based on what you provided but fixed up for syntax etc). It does not contain everything you want, but it does most of it - if I find time, I might come back for the rest:

#+TODO: TODO WAITING | DONE
#+STARTUP: logdrawer logdone

* TODO Task 1                                              :tag1:tag2:
DEADLINE: <2020-07-21 Tue>
 
* WAITING Task2
SCHEDULED: <2020-07-21 Tue>

** DONE subtask                                            :tag2:tag3:
CLOSED: [2020-07-21 Tue 15:50]

:LOGBOOK:
CLOCK: [2020-07-21 Tue 15:47]--[2020-07-21 Tue 15:49] =>  0:02
:END:


* COMMENT Code
#+name: tags
#+begin_src emacs-lisp
  (defun entry-get (prop)
     (or (org-entry-get (point) prop) ""))

  (defun ndk/entries-table ()
     (interactive)
     (let ((tbl '(hline ("Name" "TODO" "Tags" "Scheduled" "Deadline" "Clock" "Closed"))))
       (org-clock-sum)
       (org-map-entries
        (lambda ()
          (push (list (entry-get "ITEM")
                      (entry-get "TODO")
                      (entry-get "TAGS")
                      (entry-get "SCHEDULED")
                      (entry-get "DEADLINE")
                      (entry-get "CLOCKSUM")
                      (entry-get "CLOSED"))
                      tbl))
        t
        'file
        'comment)
       (reverse tbl)))

   (ndk/entries-table)
#+end_src

#+RESULTS: tags
| Name    | TODO    | Tags        | Scheduled        | Deadline         | Clock | Closed                 |
|---------+---------+-------------+------------------+------------------+-------+------------------------|
| Task 1  | TODO    | :tag1:tag2: |                  | <2020-07-21 Tue> |       |                        |
| Task2   | WAITING |             | <2020-07-21 Tue> |                  |  0:02 |                        |
| subtask | DONE    | :tag2:tag3: |                  |                  |  0:02 | [2020-07-21 Tue 15:50] |

Some notes:

• I've added a #+TODO: setting, defining the TODO states, to make the file self-contained.
• I have not worried about the LOGBOOK stuff yet: that needs fixing up, both in the file and in the code.
• I've marked the Code section as a COMMENT and I make sure in the code to skip COMMENTed sections from processing.
• The call to org-map-entries is limited to the current file and is instructed to skip COMMENT sections.
• The table is initialized with the column labels and a separator (see next item for why they are in the "wrong" order).
• We push new elements to the front of the table, so at the end we need to reverse it.
• If something is missing, it is shown in the table as nil because that's what org-entry-get returns. We can replace those calls with (or (org-entry-get (point) "....") "") to make it return an empty string instead.
• The special properties I use are documented here where you may find other interesting ones.

EDIT: Added the following changes:

• Added CLOCK and CLOSED entries in the file and the corresponding entries in the table. For the clock times to be shown correctly, you need to run the function org-clock-sum in the buffer before you try to retrieve the CLOCKSUM property, so I added a call to it.
• Added a small wrapper around org-entry-get to deal with the "nil vs empty string" problem above.
• Made the table production code into a function ndk/entries-table and added a call to it in the source block to produce the table.

I believe this completes everything you asked for in the original question.

For the question in your comment, there are a couple of ways of dealing with it: probably the easiest is to leave everything as is, but change the ndk/entries-table function to take an argument, either a filename or a buffer. We then do everything in that buffer (but still produce the output in *this* buffer). Here's an implementation (for the whole file: you can't pick just a headline with this version, but I probably won't be able to do that any time soon - the implementation could be something like this though: make the headline a second optional argument, search in the chosen buffer for the desired headline, make sure you are in the right place, then call org-map-enrieswith atreeargument instead of afileargumentorg-map-entries` is nothing if not flexible ;-) ):

#+name: tags
#+begin_src emacs-lisp
  (defun entry-get (prop)
     (or (org-entry-get (point) prop) ""))

  (defun ndk/entries-table (&optional file-or-buffer)
     (interactive)
     (cond
      ((null file-or-buffer)
       ;; just use the current buffer
       )
      ((bufferp file-or-buffer)
       (set-buffer file-or-buffer))
      (t
       (set-buffer (find-file-noselect file-or-buffer))))
     (let ((tbl '(hline ("Name" "TODO" "Tags" "Scheduled" "Deadline" "Clock" "Closed"))))
       (org-clock-sum)
       (org-map-entries
        (lambda ()
          (push (list (entry-get "ITEM")
                      (entry-get "TODO")
                      (entry-get "TAGS")
                      (entry-get "SCHEDULED")
                      (entry-get "DEADLINE")
                      (entry-get "CLOCKSUM")
                      (entry-get "CLOSED"))
                      tbl))
        t
        'file
        'comment)
       (reverse tbl)))

   (ndk/entries-table "./bar.org")
#+end_src

#+RESULTS: tags
| Name              | TODO | Tags        | Scheduled        | Deadline         | Clock | Closed                 |
|-------------------+------+-------------+------------------+------------------+-------+------------------------|
| Task bar1         | TODO | :tag1:tag2: |                  | <2020-07-21 Tue> |       |                        |
| WAITING Task bar2 |      |             | <2020-07-21 Tue> |                  |  0:02 |                        |
| subtask bar       | DONE | :tag2:tag3: |                  |                  |  0:02 | [2020-07-21 Tue 15:50] |

BTW bar.org is more or less a copy of the original file with the titles changed, and no code included.