1. I moved your post to the correct forum since this is a question about Veeam B&R and not VBO
I doubt that the size on your repository will be enough to be honest. If your server size in total is 1.5 TB, then half of it will probably be not enough. You might be able to backup once but after that you have to take into calculation the incrementals.
Have a look at this one: http://rps.dewin.me/
and fill in your data to have some idea on the size (but remember, this is a simulator and not an exact science
Hope it helps