There are a few questions on this thread about 'street focusing'. The easiest way is to use hyperfocal focusing. Unfortunately, _all_ DOF markings on both Schneider and Rodenstock digital lens helicoid units are totally useless. I think they must be left over from larger film formats.
I derived the following values from very critical 100% viewing as well as a mathematical model for DOF work.
With the 24XL lens, hyperfocal distances at f8 is 5 m, f11 is 4 m.
For 47XL lens, f8 to f11 is at 10 m.
For 100 Rodenstock digital, at f8-f11, it is 20 m.
The above values were chosen because they are easiler set on the respective helicoid mounts and are optimum f-stops for each lens when desiring max. DOF. Any further stopping down results in too much diffraction and loss of MTF.
I've also used a Bosch laser rangefinder, model DLE 50. For closer, critical focusing with the 100mm, I bought a Hassy-V back adapter, a Hassy-focusing screen for the 903 SWC and an old chimney hood. I exchange this whole unit for the Mamiya adapter/Leaf 65 unit. This ensures no focus shift issues and is easy for my work.
As for finders, another option is to buy Voigtlander finders for 35 mm and use these on a hot shoe mount on the Alpa. The 35mm works well for the 47XL lens and a 15 mm finder is good for the 24XL since the edges of the finder are not so easy to see. A 75 mm finder is OK for the 100 Rodenstock. These are small, light and work well for street type work. Since one gets immediate feedback with the digital back, I've found these finders good for coarse framing when recently using the Alpa on-the-road in Japan (but I'm shooting landscape, not people).
Overall, the Alpa was a real pleasure to use and I turned to it over the Mamiya 645AFDii that I'd brought along when a longer telephoto was not required. I only used it on a tripod as most of my exposures (all done at ISO 200) were never faster than 1/30 s and often I manually counted from 4 to 20 s exposure with B timer setting.