Questions about the characteristics of subwoofer cables

I need a longer cable for our subwoofer, now that we got some new furniture in the TV room and moved things around. I had been using an RG-58 coaxial cable, which is 50-ohm, and meant for antenna applications and it worked fine. I am inclined to make my own cable so it can be the length I want, and because I can.

Our receiver is a JBL MA510 and the two sub outputs are actually not labeled as LFE and manual refers to them as 'pre outs.' Does that mean they do not carry the specific LFE channel, but rather low pass version of the main audio? Does the sub cable need to be coaxial, or can it be twisted pair with a foil shield and drain conductor? What is the minimum AWG? This is not a surround setup; just 2.1. Thanks!