Been a while since I did them myself but the rear shocks on the 107 chassis are a little more difficult in that disassembly of the rear seat area is necessary to access the top of the shock.
The alignment is not affected by shocks except that new gas shocks are equivalent to 70lbs of verticle force a piece. This will slightly change the ride height and slighly alter the camber and toe setting if the old shocks were dead the last time it was alighned.
Bosch Master, ASE Master, L1
33 years MB technician