How to negotiate on a new car and how low can you price the car?

I'm trying to buy a brand new 2014 car and these are my options. Ford Mustang I've seen it priced as low as 17,500
Chevy Mustang 18,300. Volkswagen Passat 16,700. How do I go about negotiating and what how much do you think I can get any of these cars for priced at the lowest.

Which car for a first car?

Which one

http://autos.jdpower.com/research/Volkswagen/Golf/2001/Hatchback/index.htm (convertible version)

Or

http://autos.jdpower.com/research/Jeep/Liberty/2005/SUV/index.htm

Or

http://autos.jdpower.com/research/Ford/Mustang/2003/Coupe/index.htm

Is the supercharger sound annoying?

In the ford mustang GT, I'd like to get a roush stage one supercharger. The thing is I look at other videos and in all of them, there's a very high pitched sound. And I was wondering if that was annoying or what not. Like is it really that loud, or is it because the camera is sensitive? If it is that loud is there any way to decrease the dB?

Why do they treat the second and third gen of mustangs as if they weren't there?

What I mean is that ford example when the mustang fan page uploads pictures of mustangs they never upload second or third gen mustangs. Then when ford made a mustang trailer for the 2015 mustang they made a time lapse of how mustang evolved. They put in the 1st and 5th gen. In that one they happened to skip the fourth gen for some reason. And when you go on wikipedia to see how many mustangs they've sold they skip from the first gen to the fourth gen.

Ford Lemon Law (Lawsuit)?

Has anyone had any experience with Ford and having a Lemon? How long start to finish did it take you, and what was the outcome of the lawsuit?

Added (1). 2008 Mustang GT, Leased new, 6 months ago, already been in the shop for 30 days, 4 trans issues.