G'day from Downunder JNCT,
I love making to PC blocks, I guess you are going to do a giant block. As you are doing warm and cool tones,are they in alternate rows? You may need some light warm ot cool rows and some dark, otherwise the qlt may look like one fabric. About your other queries:
1. your choice, after you do a test with your machine, I prefer going to the dark side
2. Cutting your pieces @41/2" will be more accurate, and give you choice as to placement
3.QAYG on such small pieces may not work, and frustrate you, better to quilt when top is done.
I am collecting "bricks" for a giant block too, have made 64 bocks of the 12" blocks,, alternating light and dark rows, they sure are addictive and get rid of a lot of bits out of the scrap drawer.
Good luck and post some picks showing us your progress.
Wishing you a happy Christmas, Stasher (in my stash, where I'M warm, safe and happy)