Yes, actually your hair will dread easier because the hair has been damaged, so it will hold knots a lot easier. You can use any method and the dreads will lock up.

There are a couple methods for tightening roots
1. Twisting- This is a very easy method to use just twist the root back in forth in your fingers.
2. Clockwise Rubbing- In my opinion this is the best way to tighten roots, what you do is, rub the dread against your scalp in a clockwise motion. It has done wonders for my dreads.

Use the clockwise rubbing method or the twisting method.

You should use the crocheting method. Just thread the dread through the loop and pull it through, kind of like sewing.

Dreads do get fatter with time, because the hair that would have fallen out, builds up inside the dread. This is what makes the dreads become hard after a while. But if you want really big dreads and you haven't started them yet it's easy to make them fat, just make bigger sections. And it's pretty easy to make the bigger if the dreads are only about two months old or younger, just rubber band them together and palm roll them as much as you can. But once they are hard it's really hard to connect them, you can still rubber band them together, but you take a chance of having folds or creases in your dreads.