Brakes: They sound like cantilevers. XCM was a Suntour model; Suntour was a grouping of several companies, Dia-Compe made the brakes. Many Suntour cantis use a cone wrench for spring tension, others had one screw in one arm to adjust. They're both about the same, either works. Koolstop pads for either (RIP Richard Everett) and run the Diacompe cable hanger instead of the Shimano fixed rod for either.
Cassette: Suntour AP (Accushift Plus) and Shimano FH-HGXX (HyperGlide) are cassettes, not freewheels. Suntour cassettes are hard to get, so I would use a Shimano hub. What shifters are you using?
Edit: the bottom rim is a nicer rim, hopefully it has the shimano freehub laced to it. They use pinned connections, which is a very basic connection. Mavic's welded and machined SUP would come later and on higher end rims.
Last edited by DorkDisk; 08-03-20 at 04:51 AM.