does cartridge output level affect surface noise?

it would be the same.. with a higher output cartridge you would turn down the volume control, but all that the cartridge is picking up would be louder...including the music, the pops and the clicks. If you use a higher output cartridge, however, your preamp and therefore your ultimate sound would probably sound better. The less your preamp has to work, the better it sounds.

Less sensitive, the low output MCs are noted for their ability to pick up fine detail.
However this is of minor signicance compared with the amplification of your Phono Stage. I use an out of control high--- way too high-- gain in the phono section of my ARC SP6B followed by a very similiar circuit in the line stage. Every mote of dust sounds like a cannon shot.
Sorry I cannot report any findings of an a vs B comparison.

Yes, and no.

Some surface imperfections can cause extremely fast or large stylus displacements, which will send unnaturally fast and large transient signals to the phono. If your cartridge is already near (or above) the design headroom of the stage, such excessive transients could cause a (momentary) overload, resulting in distortion or over-amplification of the transient.

This effect will be less true with really good phono stages like yours, but the general principle is the same.

OTOH, the mere fact of changing to a HO from a LO output version of the same cartridge means that all else is NOT the same. HO cartridges produce slower transients and lower peak amplitudes than their LO twins (all else being equal of course!). This would somewhat ameliorate the effect described above.

The net result from these two conflicting factors will depend on the individual components involved. So the best answer to your question is, "It depends."

;-)