I'm having a heck of a time working with MIDI drums and volume envelopes. I suspect I am making uninformed amateur mistakes, so all guidance is welcome.
 
BACKGROUND: I assume it is viable and correct to use MIDI track volume automation envelopes to drop out notes and sections (seems easier than converting a sequence and editing). If this is a bad assumption, it may be the core of my problems. In my work-ups, I drop loops in to make a foundation, convert them to sequences, then edit and (add fills in other tracks) later.
 
BATTERY: I would prefer to use Native Instruments Battery because of the wealth of samples and ultimate flexibility. But the master volume always drops when play/record is started (you can watch the fader fall). If, for example, I use a track envelope on the kick drum to make it go silent at the start, the master volume (not the kick drum volume) drops to zero. 
 
SI DRUMMER: Envelopes seem to have no effect on SI Drummer ... not on the individual drums, or on the master volume. Different behavior and all I do is reassign the output of the track (say the kick drum track) from Battery to SI Drummer.
 
QUESTIONS:

1. What is the right/smart approach to building a drum base using loops/sequences and editing/controlling them as the project progresses?
2. Is it right/viable to use track volume envelopes to drop out notes, and if so, how to you make it work on individual drums in Battery?
3. Why is Battery's master volume responding to single note/drum track volume envelopes? How does one work around this?
4. What are the basic do's and dont's in terms of MIDI drums in terms of starting with loops/sequences and editing/controlling them as a part of the final mix?

No, it's not viable to use MIDI Volume to manage levels or note muting in a drum synth because all of the parts are being driven by the same MIDI channel so there's no way to distinguish which envelope controls which instrument output (audio) channel. There may be exceptions to this, but generally drum synths don't differentiate MIDI channels; MIDI CC7 arriving on any channel controls Master Volume, and that's it, unlike a multitimbral synth that associates a separate MIDI channel with each instrument/audio channel.
 
So instead of automating MIDI volume, you need to set up a separate Audio track to host each output channel of the drum synth, and automate audio volume on those tracks.
 
That said, using audio volume to mute individual hits is a very awkward approach. If the sequences are being played by Battery's internal pattern player, it will be much easier in the long run to drag them into a MIDI track, assign a drum map to the track so you can easily differentiate the parts by kit piece/articulation names in the Drum Pane of the PRV, and edit the MIDI to remove notes or otherwise rearrange the patterns. Just remember to disable Battery's internal pattern player once you've move everything to a MIDI track.

Actually, I never use midi volume on virtual instruments. If and how the instruments behaves to midi volume (CC 07) depends on the implementation inside the instrument. Continuous controllers like midi volume will usually affect the complete instrument, not single notes.
 
If you want to control the volume of individual notes by automation, you have to route each note to a different audio output (which is possible in Battery and Session Drummer 3, but not SI-Drums), create an audio track for each audio output, and then control the volume for the note's audio track.

I can confirm what both these gents are saying as I do the exact same thing.
Route everything to separate tracks and create a volume envelope using automation.
This is helpful with Crash hits that are cupped off quickly when a dead silence is needed.

Thanks to everyone.
 
A little experimentation in the lab says it is better to clone and edit the sequences, though in some respects tedious.
 
That being said, I'm still curious why the master volume in Battery drops when record/play is started. I checked (what I know to check) of the tracks and clips and don't see anything that should/would cause this (and I don't sense this happens in either SI Drums and Session Drummer).