Good god man, your math is horrible! Amperage is watts/volts.
76/12=6.33A for the PS2, use a 7.5A fuse.
400/12=33.33A for the inverter, probably use a 30 or 35A fuse, since you're probably not going to fully load the inverter.
You'll probably want an 80-100A fuse on the main power line.
Also, I'm having trouble reading your diagram and figuring out what is what.