What are these small propellers in the A330 MRTT's wings?
Those two locations you circled out are the under-wing refuelling pods, mounted on pylons (where, I suspect, the A340 outboard engines would be).

You can find a picture of them on the A330 MRTT Wikipedia entry, under the Design section.

And those propellers on the pods are likely the ram air turbines that power the refuelling pods, according to the manufacturer:


  Wing-mounted aerial refuelling pods feature a drogue refuelling system and an integral fuel boost pump which provides a fuel transfer capability up to 450USGPM (1703 Litres per minute) at 45 to 55 PSI (310 to 379 kPa). Pods operate with aircraft power or are self-powered by a Ram Air Turbine.