The version I and II power up from a nicad pack (most needing re-cel by now) or by the rare AA battery clip. The model III could run off CR123's mounted in the camera base or with a type III AA battery clip. A type III battery clip can be modified to work on the first two bodies. Backs are interchangeable between the systems but are slightly different Type III backs are all the same, the inserts are either 120 or 220. The original backs are 120 or 220 but the inserts are the same. The type III and IIIN backs with the III body and M series lens will imprint shutter speed and f-stop and other data in the rebate area.
For table top, get the extended wideangle bellows and the 40mm or 80mm extension rails. You'll never want to take them off the camera!
The 180mm f3.2 is a great portrait lens. This setup is way easier to use than a 4X5 with roll film back as there is no lag time from focusing to shooting.
It's a heavy beast (I tried hand holding it, just once!), but a smooth and easy to operate machine. All the knobs and buttons are well laid out. Sometimes I wish I still had one, but I'm a lazy shooter (don't like tripods)!