Quote Originally Posted by JDW22 View Post
Just to clarify, is the 500C/M's "Pre-Release Button" the method used to lock-up the mirror to minimize vibration from "mirror-slap" -
especially during long exposures?
Yes.

Quote Originally Posted by JDW22 View Post
Also, does a good CLA involve only the body or does the lenses benefit for similar attention?
Body. lens and back assuming you don't know when it was done before.