multiple batteries

I HAVE A 92 PLYMOUTH DUSTER WITH A 90 AMP ALTERNTOR ,200 AMP RELAY ISOLATOR, 5 BATTERIES IN THE REAR IN PARALLEL WITH 0 GA.PWR AND GRND COMING FROM THE ENGINE (GROUND TO THE FRAME AT THE ENGINE ,PWR FROM THE ISOLATOR TOO THE REAR BATTERIES, 8,000 WTS. TOO THE SUBS,AND  1,000 TO THE DOORS.

1)IS THIS A GOOD WAY TO WIRE THE SYSTEM?

2)DO I STILL NEED TOO GROUND EACH OF THE REAR BATTERIES?

3)HOW CAN I FIGURE WHAT SIZE FUSES TO RUN AFTER THE ALTERNATOR AND TOO EACH BAT?

4)I THINK I AM PULLING 750 AMPS,DO I NEED A 750 AMP ALERNATOR,OR 2) 375 AMP ALTERNATORS?

I cant really answer any of your questions. But why do you need 5 batteries? It doesnt give you any extra power. All it does is when the car is turned off.......you can play your system or other electronics for a longer period of time. Upgrade your alternator to a higher output....that is the way to go.