Wow, what a project you are setting up for your self! I don't want to discourage you, but I do want to give you some pointers about what may help!
You REALLY want to look at exactly what's in those batts. In general, sock yarn is made of superwash wool, which is soft and WON'T felt. Usually some nylon is added for a little strength. Some fibers will wear better and some will FEEL better. I wouldn't use an 'art' batt with nubby bits for socks.
Also I personally find 'measuring' yarn to be a bit, well, silly, for lack of a better word. And someone will probably jump up and disagree with me. But If I wanted my yarn with an exact 15% twist, I'd go buy it.
While it may be a good idea to SEE what that twist looks like, you can't expect all your yarn to look like that all the time. And I've been spinning for close to 20 years.
I like to spin my sock yarn kind of tight. I've done both 3 ply (navajo) and 2 ply and I like how the 2 ply looks and feels.
You also want about 4 oz of fiber.
Put I'm also a loud mouth opinionated pregnant lady, so take what works for you and ignore the rest.