Im kinda bewildered by all the aquarium heaters...

First off, I dont know what size i need, for instance 7.5 to 25 watt's somewhere?

Second, will regular aquarium heaters be able to burn my frog? What could I sheath it with?

Third, I'd like on that I can set the temp on, so that it reaches that temp consistently. Alot of turtle heaters heat to 78 F and then kick off. I want to keep it about 82.

I just dont know which one to buy!