You scuff up existing paint for two reasons. First, you want to get rid of any oil, grease or dirt trapped in the top layer of paint. This is the stuff that cleaners and degreasers can't get off. The second reason to scuff is to set up a physical bond for the new primer and paint to adhere to. You want to give the old paint some tooth so the new sticks better.
You'll need a large compressor, not just the typical 20 gallon variety most of us have. This is a 60 gallon, vertical compressor with typically a 5+ hp motor. Then you'll need a decent paint gun (possibly 2; one for primer and one for color) which again is an expense. Then there's the question of where you'll paint the car. Renting a paint booth is best, but can be expensive and hard to find. You can always seal up your garage or shoot out in the wetted down driveway, but you'll inevitably get dirt and moisture into the paint.
Fortunately, you can always get your primer tinted for free. Getting your primer colored the same as your paint will save you a coat of paint. Of course, I always recommend doing a minimum of 2 coats of paint so that your finish sheen looks consistent.
What are the major color fields in the painting and their role in the entire composition? Is the light optically realistic or expressive as in Matisse's painting?
There is still no standard labelling scheme for paint. The blue globe label, pioneered by B&Q, led to VOC reduction on the mass market and has been adopted by other brands, while the European Ecolabel, recognised in 15 EU member states, looks like a flower and appears on brands such as Earthborn. Germany also has a Blue Angel label and there is a green Nordic Swan as well. You will find more detailed information on most of the paint company's websites, as well as a wealth of practical and design advice.
Take your time there is no rush. There is nothing wrong with having your project take a couple of weeks.
Once you figure out which position is prime and which position is spray, place the valve in the prime position and grab the primer hose. Point the primer hose in the empty bucket near the top and at an aproxx.45 degree angle from the side (the reason for this is that there is likely to be pressure still built up in the airless and when you first switch on the airless to prime it, paint will likely burst out of the primer hose and you don't want to have it go everywhere). Now turn the airless paint sprayer on and you will see that the airless is sucking up the new paint and pumping out the primer hose. At first you will typically see a cleaning solution come out followed by your paint. When you see your paint coming out switch over the primer valve to the other position and you will see the airless pumping paint into the main hose.