About commercial use

Unless I am mistaken:

  1. Yes
  2. No (you can certainly use other software -like Blender, Maya, iClone, etc- as part of your workflow but all the MH related content must be ultimately rendered with Unreal Engine)
    Here is the MetaHuman UELA for the US: https://www.unrealengine.com/en-US/eula/mhc