Question

Many VSTs use key switches to add articulations to notes. Often these switch notes need to start BEFORE the note they are articulating.

Answer 1

If you press the "Tab" key on your computer keyboard, this will open up the sequencer overlay function where you can view note durations as well as velocites.  You can then use your mouse to drag the beginning and endings of your notes to adjust them as desired.  Simply press the "Tab" key again on your computer keyboard to get out of this mode.