Answer 1) Rockauto has shoes, wheel cylinders, etc. The Bendix brakes on your 53 were used up into the '70s and stuff is readily available.
Answer 2) I wouldn't bother. If you replace wheel cylinders, or anything else that involves opening up the system, you should flush out all the fluid and put new in after replacements.
Answer 3) Get hold of a Service Manual (reproductions are readily available) and follow that. Adjustment of the shoes is a 2-stage process. If you don't have a service manual, take pictures of everything as you take it apart to ensure you get it back together correctly. Oh and check the drums for wear and maximum diameter. If they've been turned too many times, they may need to be replaced (also readily available.)
If you've repaired drum brakes before, this should be no issue for you.
