Interesting composition... not "the average stuff"...
Since you work with MIDI already... and I am "only" a sample arranger (next to perfect though )... I'll keep my mouth shut now... you learn come time.
You 've got it... Stay on it !!!
One sample / MIDI file set at the very end (after last musical note of your track)... this one put on 0 db volume... the end of your arrangement will be better...