to the forums! Pull up a keyboard and stay a while.
Lots of questions, eh? There are no stupid questions, only stupid answers. I hope I can avoid giving you those ones!
1. The air regulator controls the pressure of air flowing to the airbrush. You don't want to try to paint models using the full pressure that the compressor can make, so you use the regulator to lower the pressure to something reasonable.
2. I don't know, I hope somebody can answer that for you. Hard to believe anything named Tornado or Cyclone can be quiet!
3.
X:
X is the amount of parts that you mix to achieve the ratio you want. IE 3:1 Paint:Thinner is 3 parts Paint to 1 part Thinner. The size of the part depends on how much you want to make.
4. I think you asking what is the proper ratio of Tamiya acrylic paint to their thinner. There is no "correct" ratio, but I think most people would agree that 3:1 is a good starting point. You really should be looking for a thin milk-like consistancy. I "eyeball" most of my measurements! Eyedroppers or plastic non-needle syringes can assist making more accurate measurements.
5. The primer is an undercoat used to insure that the paint bonds to the surface you are painting. Acrylic paints don't like to bond to really smooth surfaces, so some people recommend a primer coat before painting with acrylics. This helps prevent the paint from lifting after masking. Enamel or Lacquer based primers have agressive solvents that "bite" into the plastic forming a strong bond. The acrylic can then adhere to the primer coat.
6. By guage I think you mean the air regulator. If you are using a small hobby airbrush compressor, the answer is not really, but it is the only way to control air pressure, which can help prevent overspray and control airbrushing fine detail lines. You can buy inexpensive ones for around $10US
7. Yes, air propellent cans do work, but badly. The propellents can freeze causing difficulty when spraying, and they don't last very long. It certainly wouldn't take very long before you spend as much as a compressor can cost. You can purchase a large tire tube and refill at the local gas station for less and get better results, or spend about 3-4 cans worth and buy a 10 gallon pressure tank which you can also refill. I know one person that has a large and very noisy compressor they keep in the garage, and they bought a 10 gallon tank they just refill as necessary. Depending on how much paint they're spraying it can last 1 to 3 models.
See MusicCity's excellent articles on most of your questions...
Thinning Paints
http://www.craigcentral.com/models/thinning.aspAir Pressure
http://www.craigcentral.com/models/pressure.aspAir Sources
http://www.craigcentral.com/models/airsource.aspGood Luck!