Agree. Book the DXB-DOH-DXB as part of your long haul trip. It will probably cost about the same as just going to DXB and the EK fares allow free stopover in DXB, so you are set. From some destinations, it is cheaper to fly to DOH than DXB.

I would think a taxi from DXB to Abu Dhabi would cost no more than US$100. I believe you should agree on the fare in advance and verify that the driver will take you. They can't pick up there, so they have to drive back empty.

A private driver and car roundtrip to Abu Dhabi costs US$150 for up to 5 hours use, booked in advance, from most of the limousine companies. So I would think a one-way drop off would cost less and taxis are cheaper than private cars.

Charles