Yes, and yes :-)
1. M-PC (actually any M-Series platform suing V. 604 or later), support up to 16 (!) M-Touch units.
2. Their DMX output are additive, up to 4 universes. Universe 1-4, only require Martin hardware (any combination of M-Touch/ M-DMX boxes). Above that, and up to (128 universes in M-PC!), you will need additional licence installed on a One-Key dongle