Hi,
We tore up our old subfloor and put down a layer of smooth sided (AC?) plywood that we are going to use as a subfloor for our vinyl tile. We used subfloor adhesive to attach the plywood to the slatted wood subfloor underneath and screwed it down about every 8" or so. Some questions:

1. Should I screw more closely together?
2. The screws are slightly countersunk. Should I fill the holes with something to make the surface flat?
3. There is a gap of 1/8" to 3/8" at places between the plywood. Should I fill that gap? If so, what would your recommend?

Thanks,
Bobby