A quilter never buys too much fabric.
As to threads, it depends on what you're doing.
I use Bottom Line in my bobbin. It's a poly thread, very thin so the bobbin lasts a long time.
Hand applique: silk or Bottom Line
Piecing for machine I use Aurifil (100%cotton) in the needle
Hand piecing I use Bottom Line.
http://www.superiorthreads.com carries Bottom Line and silk threads; also Masterpiece, a 100% cotton.
Aurifil is usually available at a quilt shop.
A lot of folks like Connecting Threads thread too.