1. Does Caissa chess implement [http://en.wikipedia.org/wiki/En_passant "en passant" rule] ? 
     Yes Caissa chess implements it, as well as any other chess law known to [http://www.fide.com/ FIDE].[[br]]
     Please check [http://youtube.com/watch?v=ZUJMT8AsFZ4 our "en passant" demo] on youtube.