This feels really really really weak to me. Don't limp w/ATo; if you have to play it, come in raising to get position on the two limpers.

If you get reraised from the SB, then you can probably call if it's not too much, but only if you have a good read/stats on the player.

Raise the flop to get the button out and have position for the rest of the hand.

If he still bets into you on the turn (or gives you a check raise) you're probably beat and you can safely fold.

As far as the four card straight, the only hand I see SB having here is 88, but I think that's just thinking scared.