well played, he thought he was trapping you with his overpair

Don't worry about the pf call, this has been dicussed numerous times on this site and as long as you can in theory break someone 10 times the bet you can call your bet and a little more. I'd call up to $2.50, with a PP, more if the raisers stack was bigger (but not much more).

If the flop misses i'm out of there but around 12% of the time you can flop a set and break someone. Occasionally your set will lose but its only about 10% of the time.

These figures are estimates, but reasonably close.

1/8 is the amount of times you will roughly flop a set

pfb = preflopbet

pofb = postflopbet

win = amountwon

=((1/8)*win)-((7/8)*pfb)-((1/8*10%)*(pfb+pofb))

Or in this case =((1/8)*90%*$48.75)-((7/8)*$1)-((1/8*10%)*($1+$21.5)) = $4.23

Hope this makes sense, and i hope this is accurate, it pretty much means everytime you play that hand in this fasion you should avg $4.23 per hand.