under the hood is a plastic box full of square relays check owners manuel to see which is fuel relay pump will not work if relay is bad
A gas leak somewhere. Check the injectors and make sure the cap is on tight.
The gear shouldn't cost over about $20, and the labor shouldn't be more than about $50-70.
It is a sealed unit. TAke it off and take the bulbs out and put a rag inside and work it around with a screw driver. Check the seam to see if you can find the hole in the sealant that is letting the moisture in.
You can drill a small hole (1/8th or smaller)on the side of one of the lower corners. This lets the moisture out, then the heat of the light will eventually dry out the inside of the lens. If you need to clean off the outside of the lens I have used a product called CrystaLenz. This stuff works very well and is easy to use. For more info check out their website www.crystalenz.com
remove your starter, then you will see it. sits right above there