The Remote commander will do:
Bell On/Off
Sound trigger (activates a (random?) sound from the list in the engine (Idle sounds anyway)
Power Up/Down
PSA start (use Dir button to cycle thru the sequence)
Speed up/Down in 1 SMPH increments or faster if held down
Whistle
Coupler (then hit + for front or - for back)
Volume (+ or - to step up or down)
Direction (cycles Fwd, Neu, Rev, Neu as normal)
It cannot set relative volume of sound types (Whistle vs bell vs crew talk, ect)
It cannot call a specific sound byte (idle or engine)
It cannot set smoke volume or turn it On/Off
It cannot set max speed, accel or decel rates
and much much more. DCS has so many things in it I can't possibly remember them all.