I usually buy my thread because of color, but usually don.t buy all cotton, because of the lint. My last quilt took 58 bobbins to complete it. Needless to say, it was heavily quilted.I usually buy the cones.
I would love to be able to spray baste, but I don't have a wall I can free up for this, my friends use spray basting and swear by it. They use only 505 spray adhesive.
I do fmq only, don't use a walking foot, except to put on binding.

I FMQ almost all my tops. Before I begin, I wind 6-8 bobbins. That will last me a couple of hours. Then I will wind 6-8 more. I will use up to 1200 yards of thread on a twin size quilt. It all depends on how heavily you want to quilt. I can FMQ all day with no problems, but I can't quilt a straight line to save my life. Even with a walking foot. I'll keep trying though!

Spray basting last a long time. I buy Connecting Threads thread and mark with a pounce pad.