Help with power and fuses (diagram)
Fuses are primarily to protect wiring. They don't act fast enough to protect semiconductors typically. 

Make sure the wire downstream of each fuse can handle the fuse current. 

Also keep all possible ground current paths in mind- a 50A-fused conductor contacting a light - gauge ground conductor suitable for 3A coils could cause fireworks. 

I don't think you should connect the other side of the rocker switch to ground- just leave it open- unless it is the lamp connection on an illuminated switch.