big pot with a marginal hand

i have another hand i recently had the pleasure of being part of that i wanted to share. i know there is a mistake or two in there, so i'm sharing the hand and my thinking and would really appreciate any feedback on either my play or how you would have played it.

Party Poker, $0.10/$0.25 NL Hold'em Cash Game, 8 Players

SB: $26
BB: $9.75
UTG: $24.39
UTG+1: $32.33
MP1: $34.49
Hero (MP2): $20.03
CO: $4.49
BTN: $26.57

Pre-Flop: K Q dealt to Hero (MP2)
UTG calls $0.25, UTG+1 folds, MP1 calls $0.25, Hero raises to $1, CO folds, BTN calls $1, 2 folds, UTG calls $0.75, MP1 calls $0.75

i'm in a late position here and feel a 4xbb raise should help give me final position post flop and push out speculative hands that can do damage on a bad flop for me

Flop: ($4.35) 3 Q 7 (4 Players)
UTG checks, MP1 bets $2, Hero calls $2, 2 folds

now mp1 limped in preflop so i'm not putting him on a high pocket pair or a/k, a/q. 33 or 77 are a possibility as well as a pair of face cards. he could also be semi bluffing a flush draw here. i'm not happy with my flat call as it gives me no information at all. mistake numero uno!

Turn: ($8.35) 4 (2 Players)
MP1 bets $2, Hero raises to $5, MP1 calls $3

the turn brings a straight possibility but doubt he would be semi bluffing a gutshot, i feel he either has a set or a flush draw here that he is still semi bluffing. my raise is to try and push out the draw and gain more information.

River: ($18.35) 4 (2 Players)
MP1 checks, Hero bets $5, MP1 calls $5

the flat call of my raise on the turn makes me discount a set. i feel if i check here i give him the opportunity to bluff a missed flush draw so my my bet here is to induce a call from a weaker queen or take the pot uncontested. i don't know what i would do to a re-raise here but i feel a bet is better then a check. is this mistake numero deux?

Results: $28.35 Pot ($1.08 Rake)
MP1 mucked Q J (two pairs, Queens and Fours) and LOST (-$13 NET)
Hero showed K Q (two pairs, Queens and Fours) and WON $27.27 (+$14.27 NET)

and there we have it, i take the pot but i felt uncomfortable throughout. any thoughts on how this could have been played better to get more info earlier?