Happy to help.
As for the hot spot temp, you'll see some care sheets that say as high as 92-93. But if I had to guess, those care sheets are more than 10 years old.
I think if you were to ask experienced keepers and breeders most will tell you they keep theirs 88-89.
I know of plenty of people who don't even use belly heat. I don't use mine in the summer. I just provide a temp gradient and they're all fine.
The way your tstat and prove are set up sounds perfect. And yeah, you'll get a few degrees difference from the probe to the actual surface temps. Mine are set anywhere between 88-94 to get the actual surface temps 88-9. They're all just a little different, so it's a bit of trial and error.
That's why it so good to have the enclosure set up prior to bringing the animal home. So you're already off to a great start
And just making sure you're measuring the actual surface temps and not the substrate? Cause they can and will burrow and push the substrate out if the way.
And please don't worry about asking questions. That's how we learn, and we were all new once. Ask any questions you may have, we're happy to help and it shows you care and want to learn and provide your animal with a great home.
Keep doing what you're doing, you'll make a great snake parent.