RE: how long on the timer
It's nice to have, but not necessary... it's supposed to keep air out of you're carb's fuel line and keep more consistant fuel flow to the carb. If you don't have a header tank, hopefully you can see your main tank's fuel level easily... just do a fly-by and see how low you're getting. You should be able to mount a header tank on the side of the heli chassis if you want to. If there isn't one made specifically for your heli, you could buy the Raptor header tank and mounting bracket, and drill you chassis and mount it wherever you think best. When my heli gets down to the header tank, it doesn't run as well, so I don't do anything too brave at that point... I usually keep it close and low until it runs out of nitro.