I have a few questions about my plan to insulate a subfloor in the basement.

Let me provided the pertinent details and my purposed plan.

The brick ranch house located in zone 4a (Virginia) was built in 1965. It has both an above and below grade basement. The structure is concrete block. The front long wall and one short wall are completely below grade. The back wall and half of the other side wall are above grade. The basement is conditioned.

I plain to insulate the rim joist with 2″ thick rigid foam and seal with spray foam. I also plan to add 2″ thick rigid foam to the walls with taped seams.

After reading threads here, I thought adding 1″ rigid foam with taped seams and floating 3/4″ advantech t&g plywood to the floor would be beneficial.

The floor is currently covered with the vinyl tile which is probably asbestos in either the tile or the mastic.

I really don’t want to disturb the tile at all. So, my plan is to float the t &g advantech.
I’ve read that its best to have the rigid foam on the wall and floor touch and to tape that joint.

If i plan to add a 2×4 stud wall to the basement walls, is best to have the stud wall on top of the advantech or directly on the slab?

If its best to have the stud wall on top of the subfloor? What is the best way to attach the the bottom plate of the stud wall to the floor? Do I need to get all the way into the concrete slab for stability? If so tapcon’s? Or is going into the advantech enough?

Thanks so much for your input!