it doesn't hurt the camera's value to clean it up, and it's nice to have a clean camera. I wouldn't go overboard, though -- the brass that is showing will just tarnish again, but a nice scrub with a soft cloth and some window cleaner won't hurt a thing. You shouldn't have to remove those plates, either. Spray the cleaner on the cloth and scrub away.
And, really, don't do too good a job - you want people to be impressed with your really old and gorgeous camera. Make it look like new they'll think its a digital thingy. GAH!
do NOT use the dishwasher!