SimWardrobe (
http://www.simwardrobe.com) had a Playable Maid controller, but it has been removed from the site, probably because of incompatibility with later EPs. The site does retain a couple other controllers to allow playable Sims to do NPC jobs, but not many.
I think ex-Townies keep their jobs. One of my Sims married a Townie who turned out to be very high on the Military track.