Frank in your first message you talk about Gate coming from "Swinging gate" - I always though that came from one of Louis Armstrong's old nicknames Gatemouth, shortened to Gate. He was also called Dippermouth and Satchelmouth (hence Satchmo), and when you saw his grin you could see why. Mezz Mezzrow explained all this in his book "Really The Blues" back in the forties, which includes superb accounts of slang in the Jazz scene of the twenties and thirties
Ray