Check this out for cable rateings
As for fuses as long as you don't go smaller than what's in the amps and not larger than the cable can handle then you shouldn't have any problems.
For the main cable from the batt I would consider future upgrades and additions.
I run 0awg and all I have at the mo is a 300w inverter on a 400 active sub.
Overkill I know but who knows what I plan to do tomorrow
Also I would suggest get 1 good ground point then disto block the grounds, but that's just me.
Hope this helps