I'm not really into the different curing methods, or production in general, but I don't think Virginia leaf for pipe tobacco has been fire cured in any significant quantities since the mid 1800's -- not the Brights, orange and reds, anyway.
As for what is straight and what is blended, I'd say you pretty much have to trust the tin descriptions, or that which you hear and read from other sources. Even then, you run into problems. Mac Baren Virginia #1 is the only Mac Baren product composed entirely of Virginia leaf, albeit probably not just one variety of Virginia leaf; but you have to dig pretty deep to discover that fact. This implies that all their other products, like Virginia Flake, HH Matured Virginia, Virginia Blend, etc., have non-Virginia type tobaccos in them.
Orlik Golden Sliced (and 'little red') was widely considered to be a straight Virginia, but if you read the fine print -- I think on the little red square tins -- it says it has Burley tobacco in it. Kevin checked up on that and discovered that not only did it not have Burley in it, there was actually a bit of Perique! (And none of the self-anointed tasting experts ever suspected that!)