Welcome to the forum!

Congrats on your new snake.

To answer your questions:

1. Once a week is perfect. Just keep feeding every Sunday like you have been.

2. Feed live if she prefers it, just monitor her when you do and don't keep the mouse in there for longer than 10-20 minutes. Remove it if she doesn't show any interest. BTW, stunning a mouse is considered cruel by many. You should either feed live or pre-killed.

3. You should probably bump up the hot side to the low 90s. She may be burrying herself in the substrate because the hides are too large. You can try giving her a smaller hide to see if she uses it. They like to feel the sides of the hides against them. Also, if you haven't had a chance take a look at our caresheet.