The starter contactor is different from the main contactor. The main is grounded to close the relay, the starter relay must have power applied to power up. another way: The Van's contactor has three terminals, two big, one small, Ground the small one to close the relay. The Van's starter solenoid has three terminals, two big, one small. Apply battery voltae to the small terminal to close the solenoid.
You are showing a 5 amp fuse in-line with the shunt to the main bus.
If you are going with the plane power alternator, the regulator is built in. You only need a field wire.
I have LSIII ignition. On mine, the on/off switch is in the power lead. I am assuming that is a pullable breaker in the line supplying it.
Here is a link by GMS jet pilot:
http://img116.imageshack.us/i/altwiring5cm.jpg/
Look at this installation of the diodes around the master solenoid. Also look at the starter solenoid and diode.
Looking at your drawing, I might have my alternator wired incorrectly. My output is on the bus side of the main contactor. I'll ivestigate on this one.