Devo m from walkera qr x350pro upgrade

I´ve destroid my qr 350 pro. so with the transmitter devo f12e , the receiver rx705 and the control flight devo m.
i would like to built a bigger drone.
the target is 50minutes of flight.

I could connect de devo m and program some wp with the mission planner with good results.

anybody know if the devo m can control 6 or 8 motors?

How I choose the motor , prop and batery to reach the desired flight time?