Single Comment

Concerning your second question, the rules given on the website clearly say
that when as a result of the two synchronous moves:

'b) ... a figure moves on a field, which was before the synchronous moves
occupied by a figure of the opposite color, that, however, has been
synchronously moved from this field on another field, then both figures
safely reach their new position.  Neither of the two figures is removed
from the board. Thus, in some cases the synchronous moves can result in a
mutual exchange of the positions of the two figures that have been moved
(This is possible, even if the ways of their moves overlap with each
other).' This means that a pawn that moves diagonally trying to capture a
figure which is standing on the corresponding field (!and only in this case
such a move is allowed!), simply misses that figure if it moves away in the
same moment. Thus: if 1. e2-e4 d7-d5 2. e4-d5 d5-d4 -> both pawns remain on
the board as the strike e4-d5 misses its target, as the black pawn moves
forward. It would even be possible that: 1. e2-e4 d7-d5 2. e4-d5 d5-e4 ->
here both pawns miss their target, and as a result their positions are
exchanged.

In my opinion it is absolutely essential for a synchronous chess, that it
is possible beforehand of the two synchronous moves to decide which moves
are possible, and which moves are forbidden!!! Therefore according to the
rules given on the website: A Pawn's (or any figure's) move is legal, if
it is possible according to the conventional chess rules,- i.e. assuming
that the other would not move his figures simultenously. - It is not
possible that a move is legal before the two synchronous moves, and proves
illegal afterwards.