Yes, Clint; you can use any lens made for a screw-mount Leica body, including those from Voigtlander, Leica, various Russian/Ukrainian lenses, etc, all needing an adaptor. There are three "flavors" of adaptors, but for your R2 it doesn't matter what focal length lenses the adpators are intended for; any will work fine.
The Ultron 35mm f/1.7 is an excellent choice.
In addition, you can use any M-bayonet mount lenses, including of course those from Leica, Minolta, Konica, etc, and the two M-mount lenses from Voigtlander (35mm f/1.2 Nokton and the latest 35mm f/2.5 Color Skopar pancake). No adaptor needed for these.
For your R2 you can use any current-production Voigtlander lens with the exception of the "S" and "C" models with Nikon and Contax RF mounts, and the SL series of premium SLR lenses.
