Don't mess with him when he is sleeping with his eyes closed
I would just give him a second to wake up when you pick him up and gently take his plant away and let him wrap around your arm instead or something. But grabbing them behind the head sure isn't a way to make them calm down, they don't like that to much lol.

I don't think he would care about a little bit of warm water but make sure you change it frequently and bacteria will grow easier in it. It would be easier to control humidity and temperature in a plastic tub which I'm assuming you don't have since you are using a heat lamp. Are you using an UTH(under tank heater)?