1) You can use both, as long as you don't need to use them at the same time. (Windows combines them together.)
2a) "n/a" = the default general input, but you don't have one, probably joystick?(see BTW below); changing the general default will effect this.
"none" = game specific input set to none; changing gerenal default won't effect it.
2b) In general for all inputs, [push the button] or [move the joystick] or [spin the TB/spinner] that you want to change that game input to. The analog ones, of course, should be limited to analog joysticks and mouse type inputs (aka TBs & spinners). Please note that you need to move/spin the analog device large enough amount, and mice device types are the most picky in needing the correct amount moved. You will need to try a few times, at least. IMO, it's easier to hand edit the cfg file.
BTW, since you are getting n/a, I wonder if you enabled the mouse? If you didn't, no amount of spinning will work at remapping, and all you'll get is the "n/a" and "none". It the mouse is enabled, you should be flipping between "mouse 1 X" (or Y) and "none".
BTW2, if you didn't enable mice, you probably don't need to remap.