RE: 4 motor electric wiring
I think your ESC's are too big, those are 50 amp motors. I would use Castle HV-45's and let the current sensing limit to 40 amps with those. What props? Do the batteries fit in the nacelles? Using a 16x10 3-blade on the Kv=250 version of that motor is 14-18 amps in the air and about 40-50 on the ground. Opto-isolators and independent small BEC's will eliminate the need for any connection between the motor batteries and reduce radio interference. If you decide to go with a single large battery in the fuse' you will need 10AWG or bigger wire (the wire must be sized for the peak instantaneous current) to prevent a harmonic from building up and damaging the ESC's.