A couple of spraying questions.

Finally got to try my STAR 0.8 mm spray gun, with a LINCOLN 24L oil-free 1HP compressor. Not for a guitar project though.
Just trialing it on some 140 mm x 260 mm pine boards using Cabot's water based poly. I diluted the poly to a 50% mixture. It seemed to go on quite well, giving quite a smooth finish. I ended up giving them 5 coats - probably should have gone higher - but it worked out to be a nice finish for the project.

Soooo,
knowing nothing about spraying poly, a few questions:

1. Should the poly be diluted for better spraying? Is 50% reasonable?

2. How many coats should I expect to do?

3. I recall reading that necks are more playable with a satin finish. Is this just a player's preference?

4. Is spraying a water based poly still not recommended during times of high humidity?

Thanks for any assistance.