is hooking up the wire for the subs up to the fuse box ok? what are the wires rated at....

 

NO.

you need an independent power wire running straight to the battery.
no hooking to fuse boxes allowed!

the wire MUST have an inline fuse in it as well very close to the battery.
like within a foot.

you will need to buy a new positive battery terminal. a splitter if you will.
all major car audio companies and wire companies make them.

and the wire is not for the subs, it's for the amp.
the only wires going to subs are speaker wires.

 

Holy Fire Hazard Batman !