Some PPG paint related homework questions

I have an assignment due in a few days and I'm having a hard time with a few questions..maybe you guys could help me out a little bit. Couldn't find these answers anywhere(PPGrefinish.com,textbook,or product sheets)

1. What grit sandpaper would be used on acrylic urethane before compounding?

2. If the pot life of a product is four hours @ 70 degrees F...what would it be @ 90 degrees F?

3. What product do we use in paint to take away the shine?

4. What is a hiding sticker?

5. What is N.C.T.?

any help is appreciated..keep in mind these all relate to PPG products