Heating Questions

[Nuclear]

Ok, I have been researching these guys for a while, and I have some questions about heating right now.

What is more important, ambient temperatures or substrate temps?

If ambient, how warm should it be, I've heard many things on care sheets from 75-85, I'm not sure they can both be right. And in this case, a simple heat lamp would suffice?

If substrate, what is the best temperature for the undertank heater to be at? It needs to be warm enough for the snake but cool enough so that they dont get burned if they burrow down to the pad right? Unless, is there some way to prevent them from getting that far?
Any Advice Appreciated.

These are going to be a few of many questions I think, hope noone minds! Just trying to be 100% sure I can take care of one of these guys before considering getting one in a few months.

[Rosy-enthusiast]

I have heard 85 is good enough but they can do as far as 55-60 in the winter which is when they hibernate, but I wouldnt do it unless they are breeding. Since they live in the states they can take some cool temperatures.