Preparing to lay my first hardwood floor in a couple of weeks. I've been reading some threads that refer to using adhesive under the starter row. Doesn't that defeat the purpose of leaving an appropriate expansion gap along the wall? Also, if you're using adhesive are you not using any 15# felt between the flooring and the subfloor?
Also I have to build up my subfloor to match the height of adjoining ceramic tile. I'll be putting 3/8" plywood on top of the existing 3/4 TG plywood. Would 1" crown staples be sufficient to fasten the 3/8" and should I also use adhesive between the two?

Thanks!

I don't use adhesive for my starter rows. But I will use adhesive on the last rows,( where it's too tight for the gun to fit).

The right adhesive will not alter expansion, ( PL Premium Urethane). Applied in a zig, zag pattern. Yes...you need to cut out the underlayment.

Yes & yes, to your subfloor questions.