Do I lose my star rating and level if I change the name of my store?
No
Can I combine 2 ebay accounts?
No- well sorta
Can I change to my name if I am not a store?
Yes.
The "well, sorta" would mean closing one store and manually transferring all the listings to the other. Takes about eight to ten minutes per listing in my experience. (I moved my stock from dotCOM to dotCA when the stupid shipping cap on media came in some years ago. Took a couple of months working intermittently.)