Devin, interested in hearing your reasons for moving from Archicad to Revit? Didn't Archicad just integrate Cinema4Ds render engine?
Some super quick responses with very simplified answers:
-What type of render engine does Revit use and how does it compare to something like Vray?
Mental ray, and although it is theoretically a great engine most pro images will continue to be produced in Max/Vray
-What is the workflow like to create photo real renderings in Revit?
Similar, set lights and materials.
-Do you have to use Autodesk's cloud for rendering or can this be done locally?
No, can be done locally
-How well does the linking between Revit and 3D Studio work?
Via FBX and acceptable, but triangulation, etc complicates things
Other people will fill in I'm sure.