="what would their rationale be for operating both types"
Here is the rationale: The load factors accorss Qatar Airways network are high especially in the Medium/Long Haul routes. Qatar Airways could add frequencies but for slot constrainted airports like LHR, a larger aircraft than the A330-200 (that will only add a few seats over the A300-600R). Qatar Airways are currently looking at both the B777 and the A340-500 and more A380-800s. The rationale is that the A340-500 is more suitable for Qatar Airways for longer flights to the US etc and the B777 is more suitable for high density European and Asian destinations.
-"is QR looking long haul expansion (US, Australia?)
QR has intentions to fly to the US, they considered Australia for a while but later decided that it was too low yeild to make any profit. So I expect that for the near term code shares will be the only way that Qatar Airways will be represented in Australia.
-"will the one being leased to the royal flight be painted in the same scheme as the 310/340
The A340 and the A320 of the Emiri flight are painted in the dark maroon Emiri c/s. The A310 and Falcon 900 are painted in Qatar Airways c/s. I honestly don't know what c/s will be used for A330-200 that will be wet leased to the Emiri flight. I guess it will be in QR's colour scheme which makes it easier and cheaper for it to be converted to mainline service.
-"Finally, do you expect QR to attempt to go head to head with EK in attempting to develop DOH as a regional hub; will the Qatari government attempt to make Doha a strong competitor to Dubai?"
This is already happening, this explains why Qatar Airways has a yearly growth rate of 40%. The bulk of the people travelling from Europe on QR connect in DOH for flights to Asia. Also Qatar Airways are taking EK head on, for example QR and EK will start operation to CMN (EK already did), SEZ, Mauritius and the US in the same time frame. They also cooperate with EK for example they used to aquire spare parts together for the A300s and the A310s and they will soon for the A330 to reduce costs. Also QR and EK are in a joint venture crew training facility in Dubai.
About DOH, the airport was recently renovated and was also expanded to increase capacity from 3mln pax ro 5mln pax. The airport itself is IMO better than Bahrain and is on Par with DXB and AUH. There are new terminal / Runway / control tower / cargo facilities etc under construction that will be ready in time for the Asian Games in 2006 which will be held in Doha, Qatar