DeLouche, thank you so much for your thorough and well-researched answer.
I have considered downloading a world, but I didn't know where to look, so thanks for that! I'm afraid, though, that I am far too picky and control-freakish to just use someone else's entire world. I am not against including other people's lots, I've already downloaded a few, but as far as a whole world, unless it was built to my order I think I'd fuss. However, thanks to your links, I can search out other lots to add, thus reducing the lots I build myself and getting new ideas (I'll probably mess with the lots I download anyway--control freak!)
I've done a basic scan of all my available neighbourhoods and I think Sunset Valley as a template would do nicely, which of course opens the option of using the Sunset Valley available in CAW, which would also save me the trouble of evicting everyone and bulldozing all the lots.
I am taking a look at the tutorial link you sent, it looks pretty good.
We'll see how it goes! Thank you for all of the information!