Question Since the M3000 does not only have various effects but also EQ and compression, can I use it for stereo mastering to a 2-track device

Yes, it is possible but not recommended. Multiband compression is ideal for mastering and this is not avaliable in the M3000. For multiband mastering we recommend either of our mastering processors, i.e. the Finalizer series or the (now-discontinued) Triple-C Stereo.