RE: back tension??
Backtension has been explained pretty well but I would like to add something that really isolated the "feel" for me.The muscles that you use to keep a bow from creeping forward are the same muscles used to use backtension.This is what will give you the push,pull that will fire the release.
I actually shoot best with a wrist release called the Short and Sweet and I use backtension with it BUT I have a true backtension release that I will practice with to ensure I don't get lazy on the trigger and cheat with the wrist release.So it basically takes both for me to do my best shooting.