@Doug
1) Myco can work with samples (wav or hbw) having included or separate releases.
If your sample-set allows it, you can create custom organs having normal release and/or short notes release + medium notes release. With myco you can set the maximum duration for short and medium notes for each stop individually.
This picture is an example showing the stop Bourdon 16 from Ste-Anne Moseley with its two release subfolders and durations.
2) The same stop can be used several times but only once by manual.
when you use a stop several time you can use it each time with the same parameters or with differents settings.
For example, in a 4 manuals organ you can use 5 times the same bourdon 8' :
on Great, with original setting
on Positive with smaller amplitude level, slightly detuned by 2 or 3 cents
on Swell enclosed and with a tremulant
on Choir, with a different tremulant and transposed an octave up and renamed Bourdon 4'
on Pedal, louder, transposed a fifth lower and renamed Quinte 10 2/3'