Great! As time goes on you can always try different things, experiment to find an optional setup for your specific snake. It can be tricky to follow general guides and advice from online, because even your geographical climate may impact things differently. It is import to keep an eye on the setup and to get to know what impacts your area the most.
Excellent! If you still find it difficult to maintain humidity, give some thought to purchasing a CHE (ceamic heat emitter) like I mentioned. They cost about $10-15, but they last for years.
Hampster food is basically just small nuts and grain. It is perfectly fine for mice.
I found that buying and storing live mice can be a bit of a pain, especially when owning a single snake. When he gets a little bigger, you might want to try switching to Frozen/Thaw. That way you can just buy a bulk bag of pre-killed mice and keep them in your freezer. (They are less expensive that way, too!)
There are many posts about Frozen/Thaw here to help you.
That is perfect. Just make sure it does not jump to 95+. When you hear about heat pads causing burns it is usually when there is A) not enough substrate and B) when the heat is not regulated and hits 100+. As Kaorte said, many pads will hit 115-120*. If yours is stable at 87-92, than it should be fine. I keep mine at 92.
A suggestion about decoration: it might be good to put some black cardboard/bristle board on the back of your tank. That way the snake will feel less overwhelmed when he is out of his hides, and it will give the tank a nice visual presentation. As I mentioned earlier, these snakes don’t go out much and spend most of their lives underground/hiding. Just a thought!