etrailer dot com has good videos on everything you need.
Typically do the grease on brakes when you change your pads. Minimal grease is needed, best to look at etrailer as the video will show more than we can with words.
Brake cleaner will clean a lot, but unless you are off-roading then just normal road grime is not a huge issue. Brakes do work on the principal of friction.
If you live in the rust belt then that's a whole other story if driving in salty roads.
Yes, the bearings need way way more attention than the brakes do. Typically brakes just need to be adjusted (if not self-adjusting) and the pads replaced when worn. Nothing else.
Honestly, on mine, I do nothing unless I notice an issue.