move the play head to 5 minutes, then turn of reading of automation for that MIDI track. it'll stay at 127 (which it should be at). if you do it the other way around it'll stay at 87, until you manually adjust the fader.. heh.
if you want to use different velocity hits, then edit the midi event, and use the draw tool to edit the note velocity (it's at the bottom of the MIDI editor). if you have 2 hits occurring at the same time, selecting on of them in the note editor will make only 1 velocity get changed.
if you want to automate drum volume, then add your automation on the return track from the VST instrument. you'll probably want to enable all the return tracks (as it defaults to just one), and then send each drum to it's own return track. then you can automate just the snare volume, for instance..
and oh my science, cubase 5 is ugly!