Much of the country with VM coverage is DOCSIS. You may be able to tell if you take photos of the VM cabinets in the street or another home that has a connection from the outside.
23 years of broadband connectivity since 1999 trial - Live BQM
No way to check. Only in trial areas. Packages are identical AFAIK.
Everyone with Virgin available has access to their gig1 package (unless their area is oversubscribed).
That includes folk on older coax, newer RFOG fibre (still DOCSIS 3.1) or XGS-PON.