1. The upholsterer called it high density foam. It's not HARD hard, but harder than the normal seat foam and retains it's shape better.
2. No idea on the F150 head liner. There used to be a guy, maybe still is, named Steve, SMS Headliners. Don't know if he's still active, maybe someone will chime in.
3. All 15" ZJ wheels fit our MJs. Same bolt pattern and offset. See them HERE