you will definitely need a compressor for this, the compressor you buy really depends on what the demands are for the gun. you don't want to run out of air in the tank before the job is done, so you will need a compressor that can maintain more air than the gun uses. Modern paint guns are mostly HVLP (high volume low pressure) that is it uses a high volume of air to atomize the paint for best surface finish. True HVLP guns use 8 to 20 cfm and a minimum 5 hp industrial compressor is required. A good quality gun is very expensive, but will last forever. also a dual action or DA sander will be very helpful for the prep work, not doing this one by hand.
my best piece of advice i can give you is where to paint. i have seen many "outdoor" paint jobs, as well as garage jobs. rarely do these turn out good. you really need to find a paint booth you will be able to use. i recommend you try to locate a local renter. you may even be able to stop by a local shop that would be willing to rent theirs out on a weekend or evening, when it is not in use. the paint both will most likely be heated so the paint will cure faster. It is also a closed, vented system, so you will not have any debris in the paint if used properly. without the booth there will be more work involved after the fact, or you may have to just start over
to be totally honest, if you want to do it right, and do not have any of the tools, which can cost hundreds, even thousands of dollars, i would just take it somewhere and have it done.
painting is an art, even if its just a car, it takes a steady hand, knowledge of the tools and chemicals involved, and many years of experience.
My high school offered a class called automotive body repair and refinishing which i took for a couple of years, i think it is pretty hard to find a school for this field without paying a premium. after the classes i have taken, i am still not willing to do the painting. the prep isn't bad, so i have no problem doing that. im just more worried about the finished product. luckily i have a friend with an awesome family owned autobody business if i ever need anything.
if you do do it yourself, practice on a bare piece of scrap metal, a beater car or something else, dont want the first batch on the mazda
sorry for the long post, just my $.02
good luck with your project