Questionable play in 10k guaranteed

[SweetSchollen]

I was chip leader of my table with about 2500 when avg is like 1600. 3 limpers to me, I limp in for 30 with 8 [img]/images/graemlins/heart.gif[/img] 7 [img]/images/graemlins/heart.gif[/img] for 20 in late position. Button limps in and SB bumps it up to 140. Every limper calls to me so I call figuring multiway my hand is good. Button calls.

Flop: 7 [img]/images/graemlins/spade.gif[/img] 6 [img]/images/graemlins/spade.gif[/img] 2 [img]/images/graemlins/diamond.gif[/img]

SB(preflop raiser) checks which leads me to believe he's got over cards or else he'd try to defend his hand as opposed to letting us see a free flush. It checks to me and I put 400 into a 800ish pot. Button pushes for 800 more. It folds to me. I'm thinking that the only hands that beat me are a set or 76s because a higher pair would have reraised pre. I have no knowledge of this player's style because this is like 20 minutes into the tournament and there wasnt much action yet. I decide to call,hoping to hold up against either two overs, a flush draw or possibly an underpair. He shows A [img]/images/graemlins/spade.gif[/img] 9 [img]/images/graemlins/spade.gif[/img] which was something I didnt anticipate. He rivers his spade and I bust down to like 1000.

Do you think I played this correctly, should I have folded to the push, do you think I should have checked my hand on the flop, should I have folded pre?

Thanks for your help.
(BTW, this is my first post on these boards, be gentle. [img]/images/graemlins/grin.gif[/img])