All great questions - sorry about the confusion with VS not VA. I purchased the flight and the upgrade all through DL. It was a DL customer service rep that processed the miles upgrade, which were Delta miles. My original receipt has a DL flight number but after the upgrade processed it was switched to a VS flight number. I am not sure why the flight number changed, but I had read on a previous post that this might happen and to watch for the miles to post and if they didn't post to send the missing miles request outlining what happened, which I did (including the original receipt showing the DL flight numbers). That request was denied.
I hope that helps. Thanks for checking on the critical points.