Hard to say if the flywheel is damaged...it's actually a pretty beefy unit, and more than likely, the starter gear would be damaged before the flywheel teeth.
Changing a starter should not be a big deal, but I am speaking only from experience swapping out a VW Beetle starter...which is easiily accessible. I don't know how it's positioned in the 190E, and there may be other components that have to be removed first to gain access.
Can't answer the "ring gear" question...I don't know what a ring gear is...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car