We are happy to welcome new community members! UiPath is based on .NET framework so you can choose to work with VB or C#. Any way most of development work is done by using visual design by adding and setting up the activities that represent your automation workflow.
Most of your questions are answered (and many others) in RPA Developer Foundation course. I strongly suggest you to complete it:
Multiple question in one forums which is not a good one, check below for the answers
For this you can try with UiPath.Word.Activities package and check if those are Satifying your requirement, Else still you can import your VBA inside the UiPath workflow using Invoke VBA activity
Hi A O, as pointed by Gabriel Marin, most of your questions will be answered if you go through the RPA Developer Foundation course, which is the fastest and easiest way for you to know about UiPath as a starter. Of course, you are welcome to post your question in Forum if you encounter any technical question.