Some of your questions are difficult to answer. You're correct that furibisha is ranging rook and ibisha is static rook. I think the central rook formation you're refering to is probably an anti-yagura strategy(?) About the general goals of ibisha and furibisha; generally furibisha is a counter-attacking system so traditionally associated with gote (the second player), in simple terms an exchange of bishops tends to be good for ibisha but an exchange of rooks or both bishops and rooks tends to be good for furibisha. I've never used anaguma (badger is the literal meaning) myself, if I suspect my opponent is going to build one I go for a quick attack. I think your son means snow-roof, it's an ibisha castle but probably rather difficult for inexperienced players. My advice would be to contact George Hodges and buy copies of his now defunct magazine Shogi or Tony Hoskins for his book (I've forgotten the title), these are easily the best resources in english.
Yokofutori has a lot of forcing lines so it's not really suitable for inexperienced players, it needs study. I dont like studying openings myself so I try to play ibisha against furibisha players and furibisha against ibisha players, these openings are more to do with ideas than exact sequences of moves.
The three castles you mention are all ranging rook (furibisha) castles. These days, due to the popularity of the anaguma by satatic rook (ibisha) players, furibisha players tend to use the Fujii system. This leads to a type of mino with the king behind the silver, previously this was only used against quick attack strategies. Apart from the Fujii system the other popular opening among professionals is the yokufutori, in this case the king is left relatively unprotected.
Your link is a jungle to me. Generally I think the more European look is as difficult as playing chess with the pieces represented by letters. Go is interesting as it's a game without movement, I suspect it can be decided in reverse, from won positions. This doesn't mean I suggest anybody do this, my view is that computers should mind their own business and stop interferring with our games.
I certainly wouldn't want to play Chinese, Japanese or Korean chesses with some bizarre "western" characters, imagine playing chess with the pieces replaced with letters K, Q, B, etc. It's no more difficult to memorise oriental characters than it is to memorise quaint little statuettes. Fencer, for shogi pieces I hope you'll use the top ji only, as is done in books, newspapers, etc, not the full characters that appear on normal sets.
I've played bughouse on several ocassions. It's quite fun but normally reaches a situation in which one player is about to be mated, that player then stops moving and hopes that their partner can win before their own flag falls. I've always played at five minutes and never on the internet.