First of all, welcome to the forum and congratulations on your yard sale find!
I would not attempt to disassemble either the cameras or lenses or to clean their internal parts; removing the camera back and gently blowing any dust out of the film compartment or off the film rails or out of the film casette compartment or film take up reel area is fine, as is blowing dust off the fromt or rear element of the lens as well as the exterior of the camera and lens, but leave the disassembly, cleaning and reassembly to a professional.
This is not a push mower we're talking about working on; it is a complex precision instrument. Attempting to disassemble and clean a Leica is no different than attempting to disassemble and clean a Rolex, Breitling or A. Lange watch - it is something that should be attempted only by those who are professionally trained and are up to the task.
Sherry Krauter is most likely the finest Leica technician you will find anywhere - she has worked on my M cameras over the years and I can recommend her without reservation. She has a website
http://www.sherrykrauter.com but you will want to give her a call at (845) 496-8834. For some reason, her email server has reliability issues and your chances of not having your email to her disappear are a crap shoot.
Sherry is very old school - honest, dependable and of the highest integrity. She does outstanding work for reasonable fees and gets your camera or lens back to you promptly - usualy in 3-4 weeks, not 1-2 years as some Leica technicians are infamously known for.
Hope this information will help...