Listed as 18ga. So 20A/120 watts for runs up to about 6 feet. Any longer than that and I'd say keep it 15A/90W. Not sure what that plug is.. I'm guessing on the 4 seater that is the aux plug that would be found by the 2 seater's radiator? I think on the 2 seater, the rear aux power is always on but can't remember for sure. The front one under the hood is ignition switched.
Yes they are for accessories. The front one by the switches and middle one by the battery are only hot when the key is on. The aft one by the radiator is hot all the time. IF I remember correctly the forward and middle ones are 15A and the aft is 30A.