I would use 10k thermistors for sensors. Not sure how I would enter set-point data..... Data wheel, keypad, POT, pushbutton, etc. I admit I am a little out of date on all the new microcontroller stuff that is available. The h bridge chips i planned on using are 5amp continuous, 6amp peak. If it needs more amps I think I would go with Kecked's idea of a realy to set heat/ cool and a discrete fet as the PWM switch. I'm still on the lookout for a higher powered h bridge IC just because of the simplicity. Most the h bridge IC's have built in diodes, short circuit protection, and are easy to drive.