I have an later NC1000s which is a really nice camera - good lenses and feels a bit like an Olympus OM i.e. very compact and easy to handle.
A couple of good Mamiya 35mm websites are:
http://people.freenet.de/stauber/mamiya-nc/ - this site is dedicated to the NC series but does also have loads of stuff on the earlier M42 models such as yours. Text in English and German
http://herron.50megs.com/index.htm - a great resource for all 35mm Mamiya cameras
I used one of these from 1975 to 1998 with excellent results in all conditions. Metering with non-Mamiya lens was very easy by just pushing the rewind lever forward and adjusting the apeture after selecting the shutter speed. As others have said, the 42mm screw mount alows the use of a wide variety of lens' from many manufacturers. It's not a bad basic 35mm camera although it's limited by the1/1000 top shutter speed. Skip G