Background:

I was starting to install solid 5/8 inch oak floating it using the junkers clip system. Despite (seeming) to meet the 3/16 over 10 feet standard, i believe i have too many creaks and some hollowness. This won't work for me.

Now i want to nail down 5/8" cdx plywood. looking for some advice. Should i use tapcons or invest in a nail gun. I have 800 sq feet to do.... a lot, I know...

should the plywood be put down in 4x8 solids... should the plywood have some grooves cut into it?

I would then nail the solid oak to the plywood