That 480A is max draw. The controller pulls whatever it needs from the battery. A 160A controller means the batteries will only ever put out 160A. Also, you can definitely bring spare batteries and swap them out.
If you put them in parrallel it would only be 5s meaning you've still got the same voltage. However, yes, it would give you (theoretically) twice the distance
Edit - also, it'd be 30c, yes, meaning max current draw of 480A (twice the max draw of one battery)