A:AnswerThe computer meets the "balanced" system requirements for Revit (so more capable than the minimum requirements, but less than the "high end"), so it should be fine.
A:AnswerDifferent VR sets will have different requirements. I would look at the recommended specs of your VR headset and compare it to the installed components on this model.
A:AnswerHello! and thank you for choosing HP. Technically you can put any sum of RAM in the computer and it should work. However, you will want to make sure every stick runs at the same stick and it's from the same manufacturer.