I dont like the flatcall because half the deck is scary on the turn, the shortstacks raise isn't enough to re-open the betting, so the origional raiser can only call on the flop (assuming you call) and then ur gonna be shipping it into a dry sidepot on the turn and he would generally expect you to check away turns if u are on a draw and it comes a big ol blank.
Also raising here is perfectly ok, no idea whats going on about not raising just because its your first hand at the table/short stack behind. If you cant beat a shortstack at 50/1 when u got a pair , your in trouble.
the sb more than likely has a OP or over cards. i wouldnt be worried about giving free cards to the sb as a straight danger card wouldn't help him anyway.