DAMBUSTER

Hi,I have recently purchased a 12z after many years of J.R.I find the manual less than helpful.I want to set a count down timer to start at 25% throttle stick and run until I turn off the Tx and reset when the Tx is turned on again.I also am having difficulty mixing zero throttle stick to,lets say,5% down elevator.Your help,in simple terms please,would be much appreciated.The radio is updated to 1.6.0

Thank you Gray.
P.S. Other than my inability with programming the radio is excellent.