I am going to have those cables replaced with 2 custom cut Gauge Wire, This won't hurt any electronics would it? Would I need to do the same to the negative cable? Also will sound wire be okay or will the insulation melt?

 

Also there's a Black Cable that runs infront of the fan and down below into the block on the driverside, How is this connected as there feels to be a boot over it...

Edit: Found out this was the alternator, what sized bolt holds the cable to the alt?