As for the bikes: The Sachs Seville is the 505-A. It's in good condition, runs, very little wrong with it. I have a nicer Seville frame for it I can do a swap with, but would be more expensive. The Kreidler MP8 is whatever engine Kreidlers use. It's a work in progress anyways, you probably dont want it. The Hobbits are PA-50s. Your best bet is either the Sachs as is, or the Sachs with a frame swap. E-mail me for prices.
-Steve