C LAB Notator + cartridge is a great MIDI sequencer. Always preferred Cubase myself, but it's supposed to be great.
The monitor connector features standard R/G/B HS/VS signals, so if you have a look at the pinout you can easily make your own cable.
Regarding Magic Workbench - I've never used MW myself, but if I understand it correctly it enhances the GUI somehow? You could install MagiC or Geneva, which are fairly efficient replacement operating systems. Both are commercial, however.
