Pauley, I don't think I'm really qualified to advise on what to include in sauce. My sauce philosophy has always been to use the best tomato product available and don't mess with it; keep it simple. Especially with NY style. For many years I preferred DOP San Marzanos for NY style sauce. But nowadays I want something with the right consistency straight out of the can, that requires less processing (or no processing), even if it sacrifices a little quality. And even though 7/11 tomatoes require considerably less work than any whole tomato, I'm not sure there is any noticeable drop in quality with the 7/11 tomatoes. Right now all I can say is the more I use 7/11, the more I like them. And so far I don't see any reason to add anything to them for NY style. But that may just be a reflection of my tastes.
Also, I didn't make or eat any pizza between January and July, nor did I think about pizza much during that time, so lately I've been experiencing pizza from a totally different perspective than I have in the past. But oddly, these several months of pizza inactivity seem to have refreshed my brain and somehow created pizza knowledge or insight that I didn't possess when I stopped making pizza in January. For example, I spent two years trying to clone Tommy's pizza (Columbus, Ohio cracker crust), and I came close but I was still pretty far off the mark. Then a couple weeks ago I tried again, having not made this kind of pizza in nearly a year, with at least four pretty major changes from my previous best-yet dough, and I nailed it.
I've learned a ton lately about sauce; things I never thought about since I started making pizza in 1997. For example, if you bake a stuffed pizza for 35 minutes at 450 with a pretty simple sauce (7/11 with a hint of oregano, basil, and crushed red pepper), you really taste the oregano, and the tomatoes end up tasting very cooked. But if you use the same sauce on a deep dish baked for 23 minutes at 450, it's a totally different experience: fresh tomato taste and no heavy oregano presence.
Since I've learned so much about sauce lately, it stands to reason that I'll continue learning. And if I ever deem myself qualified to answer the questions you asked, I'll answer them to the best of my ability. But right now I don't think I am qualified.
I guess the hard part sometimes, for us home pizzamakers, is just being able to acquire the ingredients we'd like to try without having to buy 40 lbs of it. Fortunately for me, I had an accidental conversation with the guy who does all the ordering for an Italian specialty shop that carries a very wide variety of canned tomato products (including Stanislaus, Escalon, and Redpack products). Since I didn't see 7/11 on the shelves, I asked him if they ever carry it. He said no, but he said he'd order some. When it arrived, I bought two cans. After trying it, I was impressed enough that I went to a distributor and bought a whole case. (The case only cost $25.)
In an attempt to answer your question: I don't feel any need to add salt to 7/11, and although I don't like adding sugar to sauce, I can see how adding some sugar might make 7/11 more appealing to American taste buds.