PStars PLO8 .10/.25

[bbartlog]

Am I chasing like a fool here? I think an argument can be made on each street for a different play than what I made, which is why I thought the hand was interesting. Comments on all streets welcome.

PokerStars Pot-Limit Omaha/8, $0.25 BB (9 handed)

MP2 ($12.50)
MP3 ($11.30)
CO ($14.85)
Hero ($28.30)
SB ($23.20)
BB ($7.15)
UTG ($37.85)
UTG+1 ($25.70)
MP1 ($27.10)

Preflop: Hero is Button with 7[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/heart.gif[/img], 4[img]/images/graemlins/diamond.gif[/img].
UTG calls $0.25, <font color="#666666">1 fold</font>, MP1 calls $0.25, <font color="#666666">1 fold</font>, MP3 calls $0.25, CO calls $0.25, Hero calls $0.25, <font color="#666666">1 fold</font>, BB checks.

Flop: ($1.60) 2[img]/images/graemlins/club.gif[/img], 6[img]/images/graemlins/spade.gif[/img], 7[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(6 players)</font>
BB checks, UTG checks, MP1 checks, <font color="#CC3333">MP3 bets $1</font>, CO calls $1, Hero calls $1, BB folds, UTG folds, MP1 calls $1.

Turn: ($5.60) T[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">MP1 bets $5.35</font>, MP3 folds, CO calls $5.35, Hero calls $5.35.

River: ($21.65) 3[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
MP1 checks, CO checks, <font color="#CC3333">Hero bets $20.6...</font>

In particular...
- is the preflop call too loose?
- would anyone pot the flop? Top pair plus nut low with protection is a pretty good hand... but I just called because I wanted action. A mistake?
- is the turn a fold? To me MP1 seems likely to have the top straight, while CO probably has the nut low just like me. Am I just asking to get quartered by calling here?
- river bet - actually I don't think any other play here makes much sense, but if anyone else would just check/call here I'd be interested in the reasoning.