I would like to add to Henning's post and also recommend the Bessa R2. Better build quality than the R. It just feels much better in the hand. Definitely visit Steven Gandy's cameraquest website at www.cameraquest.com. I would also recommend joining the Cosina/Voigtlander mailing list that Steven runs.
As far as the lenses you can use. As Henning mentioned on the R you can use most 39mm Leica thread mount lenses. Except some of the Russian Jupiter 35mm lenses. The rear elements protrude too much on the Jupiters and hit the shutter curtain. Also, you can not collapse most of the Leica collapsable lenses as the same problem occurs.
The R2 can use all the LTM lenses with an adapter (except those listed above). It can also use any of the Leica M mount lenses.
I had an R2 for Christmas with the 35mm Classic lens. Excellent quality lens, very small. Lovely quality to the images. I'm really enjoying rangefinder photography. It's refreshing after an SLR.
Hope that helps