Oh, you can live in all of the worlds aside from vacation worlds, which are Granite Falls (OR) and Selvadorada (JA).
Yeah, it's basically run like a business! I read that you were also considering Dine Out and GTW's retail system--I prefer the former, since the retail system for me is somewhat hectic. The most stressful bakery I ever ran... I don't even want to think about it LOL. I loved running a restaurant, though. Dine Out gives you enough of a challenge to get it to a five-star establishment.
For me, Magnolia Promenade felt unfinished since the area itself is very large but with only 4 usable lots for a whole expansion pack. I was honestly mad when I saw it the first time LOL
And yes, you can definitely do that. I've done that with my main adventuring household :)