I'm preparing for engineered floating-click installation on three 2nd floor bedrooms, closets & hallway that have plywood sub-floor. I have removed old carpet, tack strips, nails & baseboards and will use Floor Muffler Ultraseal as underlayment.
I have a few questions, if it's not too much trouble...

1a) Subfloor: What type of nails or screws would you use to tighten up creeks in the plywood sub-floor?
1b) What else do I have to do to prep the plywood sub-floor?

2) Acclimating: I have all the cases of wood on the first floor and plan to do this install on the second floor in stages so I plan to do the 2 guest bedrooms and hallway first due to other work in master bedroom & bathroom. That said, where would you stack the planks...in each room??? ...so they don't get in the way of your install? And do you stack on top of the underlayment after it's installed?

3) Expansion gap & baseboards: The manufacturer's instructions say I need to leave a 1/2" expansion gap by the walls. I'm in a very humid climate and I found only one baseboard at HD bigger than 1/2" and it was 9/16". That said, what material would you recommend for the baseboards and what size to cover the expansion gap?

Thanks!