Hey Paul,
Here is my take: #1 - I don't know, though I'd lean towards saying they have more effect on trumpet players than tuba players due to the smaller mouthpiece and bore.
#2 - no, in my opinion. My thinking is that visualizing blowing warm or cool air is a useful abstraction to get away from thinking too directly about mouth/embouchure position, but is probably not grounded in reality. I don't think the temperature or moisture content of the air changes just because it's moving faster; the wind chill effect might cause such an illusion though.
Of course, I'll gladly change my vote for you if there is money at stake here. For a cut of the profits, naturally.
Chris