Learning Short Handed-Overcall on river?

[BWebb]

Well, I'm trying to learn short-handed after playing full SS forever, basically because the games are better. Anyway, MP just sat down so I have no read. I've played probably 30 hands with button and BB so far this session and both have proven to be loose passive calling stations.

I have two questions on this hand:
1) Semi-bluffing the flop, should I do it here? Against 3 players, I feel a bet will get called here by at least one person so I have no real chance of taking it down right away. Then, if my bet only gets called by 1 or 2 people it isn't really for value. That's why I checked. Is this thinking right?

2) Obviously the river. Overcall in this 11.5 BB pot?

Party Poker 3/6 Hold'em (6 max, 5 handed) converter

Preflop: Hero is SB with K[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/spade.gif[/img].
<font color="#666666">1 fold</font>, MP calls, Button calls, Hero completes, BB checks.

Flop: (4 SB) 7[img]/images/graemlins/heart.gif[/img], 2[img]/images/graemlins/spade.gif[/img], Q[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(4 players)</font>
Hero checks, BB checks, <font color="#CC3333">MP bets</font>, <font color="#CC3333">Button raises</font>, Hero calls, BB folds, <font color="#CC3333">MP 3-bets</font>, Button calls, Hero calls.

Turn: (6.50 BB) 4[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, <font color="#CC3333">MP bets</font>, Button calls, Hero calls.

River: (9.50 BB) K[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, <font color="#CC3333">MP bets</font>, Button calls, Hero....

Final Pot: 12.50 BB