I also have many reptiles including a ball python like the one you have.
Cool, actually i have three, only added Rebel to my gallery though
My smaller BP is in my avatar,thats Roxy.
I have a ten gallon tank.
And yes, the heater is fully submersible.
I have a 30 gallon filter in my 10 gallon right now.I have a ten gallon filter but i figured the 30 gallon filter would be better as far as space and suction.