Is this standard or too weak? I have several questions

[Mr. Orange]

MP2 is 19/8/2.2 ~110 hands. Haven't seen him cold call . Seems to be very solid and not overly tricky.
MP3 is 50/27/1 ~50 hands Maniac donk.

Preflop: Hero is UTG +1 with K [img]/images/graemlins/spade.gif[/img] Q [img]/images/graemlins/club.gif[/img]
UTG calls, Hero Raises, 2 folds, MP2 calls, MP3 3bets, 2folds, SB folds, BB calls, UTG calls, Hero calls, MP2 calls

Flop (5 players, 15.3 SB): 3 [img]/images/graemlins/heart.gif[/img] Q [img]/images/graemlins/spade.gif[/img] 9 [img]/images/graemlins/diamond.gif[/img]
BB checks, UTG checks, Hero bets, MP2 raises, MP3 calls, 2 folds, hero calls

Turn (3 players, 10.66 BB): A [img]/images/graemlins/heart.gif[/img]
Hero checks,MP2 bets, MP3 calls, Hero calls

River (3 players, 13.66 BB): 2 [img]/images/graemlins/diamond.gif[/img]
Hero checks, MP2 bets, MP3 folds, Hero calls

Questions:
1) Is it worth capping preflop? I don't think it is with all the other players in the hand. If it was just me, mp2 and mp3 i think capping would have been a good play to try and get MP2 out of the hand. With all the callers I think KQs would be worth capping though.

2) Flop- is a bet right here or is a check raise better? I was trying to get a sense of where I was in the hand here. I also figured there was a good chance it would be raised by Mp2 or MP3 thus helping protect my hand. Do I 3 bet here? I'm thinking maybe I should have

3) I was ready to lead any non ace but of course the ace comes. At this point I think the pots too big to fold so is it right to call down or do I try to be aggressive here?Also one of the main reason's I called was because of the pot size. In a smaller pot would a fold be right here? Say it's just 3 way with a 6-7 BB pot.