1998 Jetta TDI Electrical, Starting, and Glow Plug Problems

[DIZMO]

Here's the scoop:
I would like to sell my car, but I want to fix a few problems prior to selling it.

Problem #1: The headlights, windshield wipers, and vent fan all lose power. With that, the dash light (BRAKE) comes on -but is dim

Problem #2: Related to #1, I think, the car sometimes won't start. The glow plug light doesn't even come on.

To fix the problems, all I do is loosen up the tilt wheel lever, then rock the steering column up and down several times until the vent starts blowing air or the glow plug lights turn on again. Then all is well...til it happens again.

Problem #3: The dash light with the airbag picture comes on all the time...it means that the air bag isn't getting full power (I think). Well, I've had it checked at the dealership THREE times, and those idiots can't fix it. They said the airbags ARE getting full power.

Problem #4: I have a check engine light on, so I took it to Meinike Car Care (I know a guy = FREE). Their computer said I have a faulty glow plug - but, that's all it could say. The guy said if I took it to VW, they could tell me exactly which one is faulty. But, if you change one, you should change them all...right? So, does anyone have any tips about how to do that?

If there is anything you know that can help me, please help me fix my car so I can sell it.
Thank you all,
DIZMO