I've never heard of sugar in tomato sauce before, and none of the cooking shows with the Italians on PBS do anything like that. I'm not sure how strange it actually is given that tomatoes naturally have sugar and I don't doubt it's part of the manufacturing process on some store bought sauce, but the only real reason I can think for doing it is to compensate for low quality or possibly spoiled produce. (Edit: should point out that my grandma on my mom's side's family is Puglian, so, at the very least, it's not common to that region of Italy.)
Grits aren't a thing here, so I can't say if it's regional or not.
Sour cream is a common additive to chili because it (supposedly) cuts the spice heat. It grosses me out, personally,
I would totally put a slice of OceanSpray cranberry jelly on my burger. Can't be worse than anything else,