RE: Onboard Glow Driver...
The glow current being on does not affect engine shut off at all. That is, if your engine shuts off normally when you close the throttle all the way, having the glow driver ON won't change that behavior.
What I do with my OBGD is to program my TX (Futaba 9C) such that the glow driver is controlled by a 3-posistion switch:
UP - glow current always OFF
CENTER - glow current ON setpoint variable by TX rotary knob
DOWN - glow current always ON
Hopefully you have a computer radio that you can program something similar.
I also wire in a ultra-bright LED to indicate when the glow current is ON. I position the LED so it points directly at my face when I start the engine. This system has worked very well for me over the years. I even have them on airplanes that don't really need OBGD just for the convenience of it.