#1
Not just any switch- The switch in my Ibanez S series has a short in the fourth position. Is there any pickup switch for two humbuckers that will fit in my shallow electronics cavity?
#4
a 5way blade still will be a bit more tricky on an HH than on a strat setup with 3 pickups. its very doable though.
i assume right now you have a blade style switch, and it sounds like its a 5way already, so the work of splitting coils and stuff is already done. buy a standard blade style switch from stewmac or ebay, and just take it one wire at a time when swapping it in. youll be set!