Those threads should answer your questions. If you still have any after, feel free to ask.
Under tank heating pads are great for creating the hot side temperature. They do not however increase the temperature of the air in the cage. This means that to use one safely you have to have a probed thermometer so the probe can sit on the cage floor measuring the temperature. UTH's will get really hot if they aren't properly regulated with a thermostat (130+ degrees) A Thermostat is a must. (the second thread I posted goes over this in detail)
As for feeding you want to feed your snake rodents that are a wide as the widest part of the snake. for young BP you can also use the 15% rule.... A young BP should eat 15% of its body weight every 4-7 days
so a 100 gram BP would need to eat 15 grams of rodent (100 grams x 0.15 = 15 grams)