fics has a poberserve (or something similar) where you automatically observer all you partner games...
OK, that makes life easy
would be nice to save them together, because the save file of just your game doesn't help much if you want to look at games later (which I never do, but other people might ;))
OK, but that does not mean you have to collect the moves during the game. You coud have XBoard fetch the move list of the partner game after your own game has finished. But perhaps it is easier to store the entire game.
That's the easiest to implement, but I don't think it would be usefull in bughouse... you really want to see your partners game the whole time and also his captures pieces...
Well, t does not seem so bad to me. (But of course I never played it on a server, so I should be careful.) You cannot look at two boards at once anyway, you would have to focus your attention on one at the time. It is not obvious to me that moving your eyes to and from the other board is very much faster than having your left index finger on the F1 key (say), and pressing or releasing it, while keeping your eyes fixed on the same point. I played this game OTB when I was a student, and then we hardly looked at each other's boards. (That just took to much time, and you would forfeit for sure...) But as a start we should certainly do this, just to have an easy check that the back-end works.
