You are correct that the Beseler is common, but that does not mean it's low grade. It's a fine machine. And yes, parts and accessories will also be common and readily available.
Ilford (many pages - look around the site)
Kodak: Teaching Basic Darkroom Techniques
Kodak: Darkroom Design for Amateur Photographers
And get a 105mm lens for the 6x7 negs. An 80mm will do, also; I just prefer the 105.