That grey head looks so nice and clean. How many hours are on it? I'm coming up on 300 hours this year and may follow your lead. I really appreciate the tear down pics. I noticed the EGT locations look to be possibly too close to the manifold flange. See: http://www.ultralightnews.ca/exhaustsystems/egt_probelocation.htm It would be a good time to measure them and remedy if you think it’s worthwhile.
No real secrets. You need to take off the cover after draining the gear oil to get to 4 of the 8 mounting bolts holding the gearbox to engine. Taking off the rubber donut is straight forward. Reinstalling it on the next engine reqires a compression clamp to line up the holes. Plan on purchasing a new cover gasket. I get mine from JBM Indusries. http://jbmindustries.com
For a shop installation, some use refrigerated air dryers. A cheapo is available from HF https://www.harborfreight.com/compressed-air-dryer-40211.html Still, $400 and only worth it if you do a lot of blasting and painting. Garage Journal has a number of compressor/ dryer threads with some decent homebrew solutions.
Those are Matco MC-1's. Out of production, but you can still buy rebuild kits. As long as the rubber boots are in good shape, they should be serviceable. Not sure if you can hook them up in tandem to have brakes on passenger side.
For the record, I got a reply back from RotaxRick today saying he's never seen one crack this way either. He also says C Box gearboxes and parts are starting to dry up with Rotax going out of production on these and with all the Apex and RX-1 conversions going on now.