I am laying engineered wood 5" wide planks on a concrete floor in a high rise condo building. The marble was removed with a chip hammer. The GC has alrady laid the soundproofing material and called for the inspection. I have a few questions:

The concrete was not completely level - there were some rough spots left from the chip hammering - but he laid the soundproofing over these uneven spots. He says he plans to lay two level of plywood subfloor over the soundproofing and then lay the flooring.

1) should the floor have been leveled before installing the soundproofing material?
2) why would he lay 2 layers of plywood instead of one?
3) should he use concrete screws to install the plywood and not glue?
4) should he nail the floor to the subfloor or glue?

The condo is on the ocean in south florida.

I don't like to argue with the GC but this process just doesn't sound right to me and I'd like to hear your opinions on how I should proceed.

Thanks for any help you can give.