Devo 12 S, CC 2500, Fr Sky, APM Help needed

Hi everybody.
I recently add to my Devo 12s a CC 2500 device (bang good). After having upgraded my firmware with the 4.0.1. (5268 - feb 23 2016) i succeed in my hope to have the FrSky protocol
I would like to use the D4R II receiver, in PPM Sum solution connected to an APm 2.8 ( wiring according to the directive of APM copter copter.ardupilot.com/wiki/common-connect...radio-receiver-apm2/ )
I have red that this wiring may become equivalent to a 8 channel PWM solution.
Exploring the new screen of the Devo12 s, i found many news possibilities
PPM in : None channel stick extend
Protocol : FrSky FrSky V8 ppm
For the moment, after having bind Tx and Rx, i am not able to use more than four channels (sticks). ( For instance, unable to connect channel 5 to the switches allowing the choice of one of 6 kinds of flight)
two questions :
1) What solution must i choose to perform my hope : use this D4R II, as it were a 8 channel PWM wiring to an APM 2.8.
2) Must i upgrade my 4.0.1. firmware with the ultimate one of march 2016 ?
I would enjoy an answer in english langage.
I mean without to much slang.
From a french guy, thanks a lot
Regards

1) You can't do that. The D4R-II is either 4 channels of PWM output on the four servo outputs, or 8 channels of PWM output on one of the servo outputs. See the D4R-II manual to see how to enable the latter, and beware of using full output on the upper channels if you can avoid it, as you can overflow the PPM frame and lose sync between the Rx and FC, which would be a bad thing.

2) No, you don't need to upgrade.

mwm, thanks for the answer and for your help.
D4R II is already upgraded in 27 ms
After re-reading the instruction manual for the Rx, i do not have find anything forgotten before my attempt to use my receiver connected to the APM ; Except maybe to install the failsafe.
I will to morrow cancel this model and remake a new one.
I must say it's for me a big challenge to have the control in the same time of a new firmware/interface for the devo 12S and two more "newness" PPM sum and FrSky..
It would be for me a great help to read somebody telling : do that and that.
These two lines quoted in my first ask seems for me as it was chinese langage (it's a french way to explain i have not understood at all)
Regards

That first line has a mistake in it. PPM (aka CPPM or PPMSUM) combines multiple PWM outputs on a single channel. So saying "8 channels of PWM output on a single servo output" is wrong - or at best misleading. But the bottom line is you only get 8 channels of output in PPM mode.

mwm bonjour, (07.22 Am for me)
i will try => :
ppm in : none
protocole : FrSky
# Ch : 8 channels
And i will give back the return
Regards