StudioX is primarily for attended automation hence the need for the human user to see what the bot does as it runs.
At the moment, there is no VBA activity you can use in StudioX; although you can run macros in macro-enabled presentation or spreadsheet files. However, you can leverage the Invoke VBA Code activity in Studio or StudioPro. In a way, I think having such activity in StudioX (or a Run Word Document Macro) is an idea to look into; @AndrewHall, @loginerror, and @Vibhor.Shrivastava what do you think?
As to your second question, I think one way you can get the Word document to be saved just once (when the bot is done) is to turn off Save changes on the “Use Word File” card or the Autosave property on the Properties pane; then add a Save Document As activity as the last activity on the card using the same file path and with the Replace existing checkbox checked.
I hope this helps?