The pink salt is awesome. I used to a bunch of times, and it worked wonders on the few baby locks I've got forming on the top of my head. Definitely worth trying out.
The wool hoodie is fine. It won't hurt, at least. Some people see wool help them a lot. I didn't see any real difference. But it can't hurt. if you wrap your head in it, it'll promote a huge tangled mess, though, that you'll probably have to spend more time separating. If you wear it as a normal hoodie, with the hood up, I'd bet that the hood falls off while you sleep, so it won't make a difference if you wear it or not. Some people use them as pillow cases, which probably works best.
I use warm-hot water before I touch my head with soap. This helps open up your pores, so you can clean out dirt easier. Then, lather up, rinse with luk warm water, and do a cold rinse at the end. This soothes your pores, and helps close them up so you won't get oily and itchy later.
But like everyone said, it's probably just the length. 4 inches is a little short to see knotting. You will see sectioning, which you are, since you mentioned "grouping". That's prefect. It's exactly what your locks should be doing at this stage. Just give it more time. When you wash, it may undo itself a little. But again, that's normal. Even people with longer hair see this sectioning undo itself with washing, sometimes