While I can't speak to much of what you are asking, I do have a few answers. While I lived in the SF Bay Area, zone 9-10, we grew citrus. Many citrus trees are really more shrub-like, so the height issue shouldn't be a problem. You can get plenty of production out of a 8 foot tree. And from a single Meyer lemon we would get 200-300 lemons a year. Meyer lemons are sought after fruits for fine dining chefs and foodies. Citrus are nice because there isn't a big rush to harvest, they keep well on the tree, in fact, better on the tree than off. Some citrus are more cold tolerant than others, I would go for those.