I had a nonfunctioning outlet in my bathroom. I decided to replace it with a GFCI outlet. Since I couldn't find out where in the walls that the wiring was bad, I capped off all of the old wires and ran new b/w/g wires to the closest junction box, which was to a dual-pole light switch in the hallway. A friend with some experience helped me wire everything, but the GFCI outlet only has a green light when the light switch is off. I would like the GFCI outlet to work no matter what the light switch position is. The junction box currently is set up like this: b/w/g (from GFCI junction box) and b/w/r/g to light switch. The ground wires are pigtailed together and one runs to the light switch. The black wires are pigtailed together and one runs to the bottom of the side of the light switch shared by the ground wire. The whites are pigtailed together and one white runs to the bottom of the light switch, and the red wire is connected to the top of the light switch on the white wire side. The lights work perfectly with the dual switches as currently wired. However, the GFCI outlet only has a green light when the switch is off, and the tester says that the hot and neutral are reversed. When the switch is on, there is no green light and the tester says that the hot and ground are reversed (and the green light comes on when the tester is inserted). The circuit never trips, though. All of the wires (b/w/r) going to the light switch read hot according to my tester. Where is the neutral? Am I really supposed to hook up the bare grounding wire to the hot side of the GFCI? I'm so confused...I've uploaded two pictures of the light switch wiring, if that helps. Thanks in advance for helping out a poor lost soul :)

I'm redoing some wiring (I posted previously regarding my air conditioning) The previous house owner or whoever did the job put a machine screws with a washer and a nut is it safe? If not what could I use? I have tones of those green screws but the box doesn't have any threaded holes. Also the black cable on the picture does the jacket has to be cut flush with the hole opening of the box?