I'll try and answer your questions for yeah .

1) Pam isn't something you have to use all the time. Only if you have a mite problem or a new snake. Even with a new snake, it's not a rule you have to use Pam. To be safe, use it once when you get it and your golden.

2) set the temp of the uth to the glass. Your snake can and will dig through the substrate until it touches the glass. Then if your at 100 you will burn your snake. No matter the substrate, always base your hotspot by the closest the snake can get to the heat source. In short, the glass should be 90.

3) why are you using Pam?