Welcome to this board.
1) Old threads don't die, people stop responding to them. There is a very long thread about T206s that kind of encompasses all of these surveys now. Plus, there are some new T206 websites that seek to answer these sorts of questions.
2)
https://www.psacard.com/auctionprices/ is a resource to see what these cards sell near. PWCC's website, VCP, or Worthpoint may help you as well.