#1
Generally speaking you want to keep your pair intact i.e. you do not want to trade away your bishops' pair. The exception is of course when the resulting endgame B vs. N is a win, usually when this is your good bishop. That is also why you should place your pawns such that the reaminig bishop is a good bishop in case of a bishop's trade.
When I have the bishop pair and my opponent has a bishop and knight, I get in many situations where my opponent wants to trade off the same colored bishops. Should I be looking to hang onto my bishop pair in most situations? I know this is very much dependent on the flow of the game and the specific position, but when is it advisable to give up the bishop pair? And when should I look to keep them on the board as long as possible?