1. Is there an ADSR command that I can use in an instrument to sound like a cymbal? If so, which instrument do I have to apply the ADSR to?
2. Can an ADSR command be taken off a channel/instrument? i.e. channel #1 has ADSR (random number) $ED $2F $89 and I want to take that ADSR off so the instrument sounds normally again in the middle of the song.
1. ADSR is not to be used to change samples or anything. Cymbal's instrument is @22/@23 in SMW. However, they have fixed gain/release rates and with that not editable on the fly in MMLs (from my experience). Using samples is your best way to get another cymbal.
2. Best to do that is to start the channel/instrument with $ed $7f $e0 (plays the note at its full length), change your ADSR to anything inbetween/wherever you like and once you want it to be restored, use $ed $7f $e0 again.