Thanx again for taking these issues into consideration!
So, for the first issue, the best thing will be having the same number of preset for AM drum kit than for the standard drum kit (that would be great because this kit sounds good!!). Or, at least, using the original drum kit samples for the unused AM samples. Probably a lil complicate to manage i supposed.
Im ’ not sure to understand your trick : “To avoid this buggy behavior I suggest using one MIDI-track for each instrument”. To arrange this issue, i’m using two midi track, and move the event from the AM rock 1 track to a standard drum rock kit 1 track. Then i delete here the “ghost” midi notes (which become available with this midi track) and removed the event on the AM track. Perhaps this procedure is what you refer to?
I can manage things like that. More important would be to add one or two toms on the AM rock kit 1 (only two toms are available on this kit, that 's not enough for my taste).With your updates, i’m becoming more and more “hard to please”!!! 
Great job by the way!!