Upvote:1
I applied for a Visa D as a researcher to Austria. I too had the same questions, so I just walked into my visa appointment with those areas (ie. duration of stay and date of expected departure) blank and explained to the visa official that I was unsure of what to fill in given that I was staying for quite a long time.
In short, the officer told me to leave the "duration of stay" blank and to fill in the date of departure as the last day of my program. In my visa that is shown as "XX".
Regarding your insurance question, my institute provided an insurance document which the consulate accepted for my visa. So no need for extra insurance in my case and I suspect the same for your situation.
This is from my experience. I would recommend you go in with them blank and ask the official face to face.
Edit: Just realized you have to go through VFS, something I didn't have to do as I dealt with the consulate directly. Have you called VFS? They can usually clarify these questions over the phone.