for the last several years all I've done is wash and quarter them, and put them in a gallon freezer bag, and squish a bit to get the air out. I started doing it when I didn't have time to process them due to my work schedule. Then I'd take out 10-15 bags, let them defrost and then do up a batch of sauce and can it.
Now I've just been taking them out and making a single batch as needed. I'm not putting up near as much as I once did, found with just DH and I, we didn't go through it much and it's a lot of work to do to give away. I'd rather give away jams and jellys, not tomato sauce. My kids love it, but they live 1600 miles away so not practical.
If you are water bath canning, you need the extra acid to make sure the acid level is high enough, but it serves no purpose when freezing. Salt is only for taste.