It's not really worth worrying too much about the lens variant, especially not for speed. The Sonnar is 2/3 of a stop faster than the others, but how often are you going to try to use that with a scale focus camera? The Sonnar, Tessar, and Triotar have different characters, but by f/5.6 or so they're all similarly sharp (maybe f/8 for the latter), and it's those middle and smaller apertures that you'll most likely be using, at least if you like your shots in focus.
I've been using hearing aid batteries in mine without problems. They seem to last pretty well. The meter's a little off (maybe a stop) but I really don't use it much anyway.
For general use, high speed film is usually a good idea in scale focus cameras, as it allows you to use smaller apertures, which in turn helps to make up for focusing errors by offering longer DOF.