Thanks to you all and lots of lurking, I now have a list of things to not do.  However, I have impaired search skills: I'm sure I'm not the first person to want to do this.  Can I safely delete (and if so, how) the neighborhoods I did things I shouldn't ought to have done in before I knew better?  I did all the delete sims from bin, move occupied houses between neighborhoods . . . all the things the game is made to look like one ought to be able to do and apparently shouldn't.  I've only had Sims 2 for a couple months, so I haven't seen any BFBVFS, but I did see some preliminary signs, and, well, why bother keeping neighborhoods I messed up before I knew better?
Also, I downloaded the batbox--but my latest expansion is Seasons.  I didn't see variant versions depending on expansion packs.  Is that right?  I'm slowly downloading other Awesomeware as I figure out what I'm doing and what it is, also some other hacks that seem to (not particularly good with computers, though I can fake it) get along well, mainly Simlogical.  Sims must homeschool!