Hi, I am a professional certified mechanic, with an engineering background, and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice, so feel free to add any additional info at any time.
That is a big bus. There is a Chinese copy of a Binks #7 paint gun that is about as good as it gets for an inexpensive paint gun, unless you have a pressure pot setup. This spray gun will need a lot of air, and at least a 5 horse power compressor. You can get one at the link HERE. I would go over it all with a DA (Dual Action sander link HERE) sander and 180 grit sand paper. These use a sand paper with an adhesive on the back. It is available in rolls of pre cut sheets with adheaive on the back. This is what all the auto/truck paint shops use. Feather out chips to blend them in. If the paint on the bus is sticking good there is no need to remove it. You just need to smooth it, and sand it where the new paint will stick. Primer any bare metal spots with a quality primer, a lacquer base primer is best because you can spray ANY paint over it. Then a final sanding with 320 grit sand paper. Wet sanding will produce a great smooth surface. Wet sanding is done with wet/dry sandpaper, this sandpaper is water proof. Water carries away the sanding dust, makes an extra smooth surface, and makes the sand paper last a lot longer. The best thing about wet sanding is it produces a super smooth surface, for the new paint. Then if you want it to be real slick, before painting it spray it with primer surfacer, and wet sand it again with 320 grit, wet sanding is the best method. The primer surfacer fills small scratches, and improves the surface. That will leave the surface as good as you can get it. As far as paint I would use an auto motive acrylic enamel, if you can find it use some polyurethane additive. You will need at least 5 gallons of paint, probably closer to 7 gallons depending on the paint quality, and whether you are changing colors. You will need 3 to 4 coats. The polyurethane additive makes the paint a lot tougher, but it is very toxic to breathe. You have to wear a respirator when toy use it. Don’t try to get away without using a respirator for any reason with the additive. I know this is all a pretty complex process, and it is tough to describe it all in a few paragraphs. Go over all of this and if you have any more questions at all, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.
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