A:
Yes I was able to.
The only problem is that the casing on the rocketfish adapter does not let the HDMI queeze in properly. What I did was remove the casing on the rocket fish part that goes into the xbox and that allowed enough space for both to fit comfortably.
Its funny that the system software has an option to use both plugs simultaneously but the design of the xbox console connection holes is so compact that they will not fit comfortably without alterations.
BTW because your not opening the xbox and not messing with xbox original parts, opening the casing does not void the warranty.
On the other hand using 3rd party hardware might, Im not sure.