Delta Flight and upgrade questions

Hi,
thanks in advance for any advice on this -
I have a Delta flight booked from Edinburgh to New York and return in October this year.
I booked through a third party and have been on the Delta website and the itinerary is there.
Two questions -
1 - When I was on the Delta website, I seemed to have secured free seats in 'comfort+' cabin. Is this common or will I soon get some kind of invoice (nothing showed up on screen as I made the seat selection and it did appear to show 'Free')
2 - I have a batch of Virgin airmiles (around 57,000). I wondered if it is possible to upgrade the Delta flight to business class using airmiles (even one-way)? If so, do I just call flying club or Delta?
thanks in advance for any advice on this -
I have a Delta flight booked from Edinburgh to New York and return in October this year.
I booked through a third party and have been on the Delta website and the itinerary is there.
Two questions -
1 - When I was on the Delta website, I seemed to have secured free seats in 'comfort+' cabin. Is this common or will I soon get some kind of invoice (nothing showed up on screen as I made the seat selection and it did appear to show 'Free')
2 - I have a batch of Virgin airmiles (around 57,000). I wondered if it is possible to upgrade the Delta flight to business class using airmiles (even one-way)? If so, do I just call flying club or Delta?