Jerricho
I'm not sure I can answer all you questions but from a pilots point of view we are legally bound to follow TCAS RA instructions even if this conflicts with instructions from ATC. As TCAS does not act in the lateral plane these instructions will be to climb or descend. Our airlines proceedure when receiving a TCAS RA would be to level the wings if in a turn, disconnect the autopilot and auto throttle and smoothly rotate the aircraft to the requested rate of climb/descent. Therefore if ATC give us a command to turn whilst we are in the middle of a TCAS RA we would not be in a position to comply with that request.
If an aircraft was climbing towards the base of a holding stack I would expect the climbing aircraft to receive a command "adjust vertical speed adjust" command and the other aircraft to receive a "monitor vertical speed" command. The holding aircraft should not be asked to climb . If the aircraft climbing into the stack ignored the RA and continued to climb. The holding aircraft may very well be asked to increase climb or even change to a descend command. Interaction with the aircraft higher in the stack should be very limited as TCAS can usually sort out the problem with small climb and descend imputs. Hope this helps??