1. Pawn pushers are not annoying. They are overextending, creating there own weak spots and that is good for me. Pawn pushers are nice.
2. Not too sure about your trading knights thing as a general rule. I would say:
a) trade knights if you expect an open position, then indeed your bishops become stronger. But often pawn pushing leads to closed positions and then your knight is stronger then your bishop. Keep them.
b) the general rule: only trade if it strengthens your position. No matter if it’s a knight, a bishop or something else.
pawn pusher are very annoying it tends to push pawns to cramp your position and trap your bishop, my advice are simple counter push your flank pawns to disrupt the pawn chain and also create an escape square for the bishop, exploit their back rank pawn and if they defend it look for weak square and checks to disrupt the position even more, thus collapsing their structure,
also trading knight is very good as their pawns become an easy picking and your bishops are becoming stronger.