Starting my dread journey!
Well first... You don't want to spray your hair with sea salt unless you plan to wash it out within 2 hours. Salt dries out your hair and scalp, which is helpful, but too long an exposure and you can make your hair brittle, your scalp break out, and everything itch out of control. So wash, like you said, wash 2 times a week, but only use the salt those same 2 times a week. Spray it on. Let it sit for about an hour or 2 and then do your normal wash.
I have an 8 ounce spray bottle. I add a descent squirt of Jojoba oil, about 10 drops of Teatree, 10 or Rosemary, and a couple of peppermint. Then just a dash of salt. Fill the rest of the bottle up with water. And shake well before each use. Sea water is about 3.5% salt. So you want your spray to match that as close as possible. Eagle might know the exact measurement. I just tweaked mine till I found what worked best. When I have time, I'll do the math and figure out how much there should really be.
As for wanting locks that are roughly the same size, just separate them so they don't get too thick. They will naturally section themselves pretty evenly, but just keep on top of it. About 1-2 times a week is good once they start to actually tangle. Don't worry about it for the first little while. Just wash and relax