Does anyone know if Adam was definitely a Warlock? If so, it would have been cool to see the show go on longer seeing him use magic powers.

According to "Adam, Warlock or Washout?" on Bewitched he did have the power (but Dick Sargent's Darrin had terrified him so much he never used them). However, according to the "Tabitha" TV series he did not and turns out he was actually born before Tabitha...Samantha had some explaining to do on that one.