As long as you have the right temps and humidity as well as a lot of hiding places, your enclosure is fine. Ball pythons don't like wide open areas and prefer things snug, but if you just basically give them snug hides within the bigger enclosure allowing them to move throughout it from hide to hide while feeling safe, they will be fine, just like in the wild. Balls don't need tall enclosures as they don't really climb much.
Your snake is getting used to his enclosure! He's scared and will hide.As long as he feels safe in his hide, it's all good. He may be moving around while you sleep.
just make sure your temps are right, humidity is right, and you have hides. After that, everything else is easy.
Substrate.. What you have is fine, just make sure you spot clean and switch it out when it gets dirty. Newspaper even works.
As far as feeding...make sure the prey is about as big around as your snake is, that's a good size. Don't go more than 1.5x the size of the widest point of the ball python. So, 1-1.5 the size is good, but try to get the prey as close as you can to the ball python's width.