New Rules in Seirawan Chess?

I just bought a set of elephant and hawk pieces from House of Staunton for Seirawan chess but I noticed some key differences on the product page from the game as described on www.seirawanches.com

For starters, it was listed as Sharper (Seirawan) Chess. This, I know, is an amalgam of the creator's names (Yasser Seirawan and Bruce Harper). Seirawan Chess just sounds so much cooler to me and that's all I've ever heard it called, so I don't really understand why it needed to change NOW after several years since the game's inception. Any thoughts on that score? Perhaps GM Seirawan is humble to a fault...?

Additionally, the pieces have their movement described as being pure leapers, like knights, but that only move in straight lines. The elephant can move 1 or 2 squares in any direction regardless of obstructing pieces, and the hawk can move 2 or 3 spaces in the same fashion. This is vastly different from the rook/knight, bishop/knight movements (borrowed from the Chancellor and Archbishop gothic pieces) heretofore described on seirawanchess.com. Is anyone privy to the logic behind this change? Even speculation would be welcome.

not sure, follow either of the rules or like I would, make up your own

I played some games of Chess 2: The Sequel on Steam the other day.  It is a really cool chess variant that utilizes the Hawk and Elephant pieces.  You can buy it online and run correspondence games if you can't find people to play Live.

Here you find the explanation. This is another game, with elephant and hawk, but with different rules and additional new pieces: http://www.musketeerchess.com/2.html

Is it possible to castle kingside with an elephant on h1? (in case the rook gets captured earlier)

In Musketeer or in Seirawan? I don't believe you can do that in either, but certainly not in the latter.

Seirawan Chess obviously. In some other custom variations it's possible to castle with Chancellor piece. 

I play with it, among other things, the chess variant "Shako" with cannons and elephant

good idea! I print for me the chess boards on paper, but in Plastic would be great and I would immediately buy a 10x10 board. or maybe 8x10 or 10x11 or 14x10 ....? difficult ...