The amount of thread will also depend on the density of your quilting as well. But if you plan on using white, you'll use that on other projects, so it is probably safe to purchase a large spool. As for brands, there are so many to choose from. I am partial to Guterman cotton, although the poly doesn't shed like the cotton threads do. I've also used Coats and Clark, but Gutterman has a better color selection. If you like varigated, the King Tut is nice (but expensive) and you'll likely need to use a larger needle, because the King Tut tends to be thicker.