As for the 2 questions PackinMama listed, no, you do not have to ask those to be legal. They're a good idea, but not required.
All that's required for selling is that you're both residents of the same state and you don't have reason to believe the buyer is a felon or otherwise prohibted from owning/posessing a firearm. You don't have to actually ask about either point, but it's a good idea. You could also reasonably determine residency through other means (the buyer's phone# is a TN area code, they have TN plates, they're active on a particular TN gun owners' forum and have posted about TN specific stuff, etc.)
That's why lots of sellers here require to see at least a Tennessee DL (proof of residency) or an HCP (proof of not being a felon). It's a good way to make a reasonable judgement that the buyer is qualified to buy. The BoS is an extra step that some buyers/sellers want to do, some won't do, and some require. It's all personal choice on that one.