NO, The Pixie 7P is not reversible. It'd make a fine weapon ESC, but you wouldn't be able to turn or go in reverse.
The current the motors pull will depend on the gear reduction, size of your wheels, and the traction you get. The odds are that if the motor is stalled, it will burn up just as easily as the ESC will.
If your motor is listed, or you know all of the stats on your motor, the Tentacle Torque-Amp hour calculator can be useful to find (approximately) how many amps you should draw.
http://www.architeuthis-dux.org/torquecalc.asp
The Banebots 3-9 is the closest thing to the Pixie, but depending on your gearing you it may go into thermal protection mode, but the good news is you can't blow it up. Or you could try a Sabertooth or Scorpion, though they are much bulkier.
Edit:Added more info