Hi,
1. it depends on your workflow and your preference
Personally I try to have all FX except MIR in my DAW to have all FX in one place. But somtimes I equip a simple EQ before MIR in VE.
(Routing in Cubase is not that complicated and you don't need much FX channels most of the time. Just use the insert slots.)
3. VE Pro is capable of surround input / output. The encoding and export functions are dependend on your DAWs capability (Cubase 10 can do it).
Best, Ben
Ben@VSL | IT & Product Specialist