Regarding two hands on the throttles, or thrust levers during take off comes from a multicrew operation where the pilot flying (PF) will advance the throttles to the approximate thrust setting. The pilot not flying (PNF) or Flight Engineer as applicable will follow through with his hands behind the thrust levers and fine tune the setting before announcing, "Thrust Set". Usually at the 80 or 100 knot call the PNF will then remove his hands from behind the thrust levers in case the P.F decides to abort the Take Off.