Single Comment

The only advantage in sticking to orthochess rules as much as possible is
to simplfy describing/learning the game. But this doesn't really apply to
complications such as e.p and castling.

It is reasonable to use e.p. if the Pawn has a double step--but it isn't
a given that the Pawn should have a double step. (It works badly on a 7x7
board, for example). 

E.P. isn't the only reasonable alternative, either. I rather like the
Nova Chess rule that prohibits a pawn from moving thru a square where it
could have been captured by another pawn if it had stopped there--this
works especially well when there are several pawn type pieces in the
game.

Similarly, if you have castling, it is good if it is similar to
orthochess, but whether to have castling is a design decision based on the
overall character of the pieces and the game. 

But again, ortho castling isn't best for every game--free castling suits
some games better.