Pot considerations and folding?

[FrogMouth]

Playing Party $25 NL table last night I the following happened:

Party Poker No-Limit Hold'em, $0.50 BB (6 max, 6 handed)

SB ($24)
BB ($11.40)
UTG ($68.50)
MP ($2.45)
Hero ($32.05)
Button ($30.25)

Preflop: Hero is CO with A[img]/images/graemlins/spade.gif[/img], A[img]/images/graemlins/club.gif[/img].
UTG folds, MP folds, <font color="CC3333">Hero raises to $2</font>, Button calls $2, SB calls $1.75, BB calls $1.50.

Flop: ($8) 2[img]/images/graemlins/heart.gif[/img], 4[img]/images/graemlins/diamond.gif[/img], 5[img]/images/graemlins/heart.gif[/img] <font color="blue">(4 players)</font>
<font color="CC3333">SB bets $3</font>, BB calls $3, <font color="CC3333">Hero raises to $15</font>, Button folds, SB calls $12, BB calls $6.40 (All-In).

Turn: ($47.40) 3[img]/images/graemlins/heart.gif[/img] <font color="blue">(3 players, 1 all-in)</font>
<font color="CC3333">SB bets $7 (All-In)</font>, Hero???

Now, 2 questions:
1) I'm pretty sure I'm beat by the SB at this point, (BB is a Chump) although I'm not 100% on my read as SB has only been at the table for 30 mins or so. What are my pot considerations as to folding the $7 all in bet? Should it be a decision based on gut and read, or should I be considering whats in the pot and how much to call?

2) On the flop, I know I'm ahead at this point and I want to take the pot down here. Should I have gone all in? How should I bet according to my opponents stacks and pot size?

Any other comments are welcome.
Thanks