While I am not a Leica shooter, I do appreciate information like these as one never knows when one will need them. Thank you for doing this, and I am sure the experts will chip in with more info.
direction of light through lens and into camera - just to orient you which is the front of the lens
My question was about why they go right to left, instead of the conventional left to right direction. It's a bit like being curious about why South is at the top of some maps and at the bottom of others.
1. how do you define best ? the lens with the most resolution across the field and high contrast is the current version. many believe the D/R and Rigid Summicron are best for B&W photography since that lens has med. contrast but high resolution.
2. Best build in D/R and Rigid.
3. again tough question - it "depends" on your need. The best for wide open photography with very good contrast and resolution is the current version