Need help with electrical on my build!!

[HobbiestBasshead]

Hello, I have some questions regarding my planned install that I’d appreciate any guidance/help/tips for. I will be setting up my electrical to feed 3 amps: Taramps Big Boss 8k, JL HD600, and AudioControl D-4.800. The subwoofers are a pair of Sundown 15in xv3s wired to 1 ohm. 

 

1. I currently have a Mechman 400 amp alt, an Odyssey AGM (under the hood), a Glowe LiFePo Series 2 battery in the back, and an Ioxus UltraCap next to the rear battery. Would a single run of 2/0 Sky High Oversized OFC wire be enough to connect the AGM to the Glowe Lithium? Or do I need 2 runs?
2. Considering the 2/0 run would be about 20 feet (Tahoe), would 400 amp fuses be appropriate or too high? Plan to fuse under the hood and then again once the wire is in the cabin. 
3. I plan to use 1/0 KnuKonceptz Kolossus OFC to connect the Glowe Lithium to the Cap via a fuse block in between. Would dual 1/0 runs from the Glowe to the Cap be enough? Are 300 amp fuses ok for each wire about 2.5 feet on each side of the fuse?
4. Lastly, I’ll have two 1/0 power and grounds (about 2 feet long each) from the Cap to the Big Boss. Is this good enough or should I add dual inputs?

 

This is just for pleasure, not competing. But every few years I get the urge for something a little bit louder. Again, appreciate any advice! Longtime lurker.