#2
Make sure the neck can handle the added tension. It might be a good idea to use drop tuning. Also, check your intonation, since it will likely change. Lastly, the nut may need to be recut for the larger strings.
#3
Such a small change shouldn't make much of a difference.

The claw on you tremolo springs may need to be tightened slightly but most likely not.
#4
Yeah I've normally had 11s on my old strat and its not that much of a big deal, though I prefer the 10s on it. Might make the tremelo a little bit harder (can remove a spring in the back to make it easier), thats about it.