[Elpa package] Emacs chess questions/issues

[Seweryn]

Hi emacs chess users,

I tried emacs chess library from elpa and found some issues or
undocumented behaviour. I contacted with the maintainer of this
package however due to lack of time he cannot address my questions
now. In the meantime, I would like to ask those questions to
emacs-chess users.  

1. How to cancel or revert moves and restart playing the game. Typing
   "<" does not allow it.
2. Why in chess display mode you cannot type ":" to eval-expression ?
   Is ":" binding unset? For example I would like to check if I am in
   editing mode with (chess-display-active-p).
3. I have chessboard in edit mode with "C-u M-x chess RET none" then I
   yank a fen position with C-y. How to then start playing against a
   specified (or default) chess engine?
4. Are chess squares and pieces in chess display buffer scalable?
5. I have a pgn file with a game open in a buffer (pgn mode). I show the
final position typing
   "SPC". Last move was done by black, then I what to continue with
   moves in edit mode, but I cannot move white pieces since I got a
   message that it is a black turn.
6. Is is possible to get a buffer with calculation of moves done
   by chess engines?

Regards,
Seweryn