Hello blankenshipb, welcome to the forum. I will try to help answer your questions but there maybe several correct answers to the same question. If you would like additional solutions, try typing your topic in the search box in the upper right hand corner. You'll get a flood of info!
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1) I can't answer this question directly because I have tried acrylics and didn't care for their performance. Many do use them and get stunning results. I would suggest that you seriously consider getting an air compressor you'll get a more consistant air supply and will save a lot in no time.
2) On your second question, a little goes a long ways in 1/72. I would hope to get 2-3 planes done with one bottle of paint. Remember thin coats are best as they don't obscure all those wonderful details you worked so hard on. You will also be thinning your paint so think of the original bottle as concentrated. I like to thin enamel by 1/3 to 1/2 with thinner, remember it is much harder to take the thinner back out than put it in.
3) I don't use any masking unless I want a hard edge to the pattern. I use a soft, non sharp lead pencil to lightly draw the pattern on the plane after spraying the main camo color. I would suggest you start with the darkest color first for coverage reasons. I then fill in the pencil outlined area. It's not unlike coloring a picture.
4) As for masking, there are different ways of doing it. For the most part I like to use 3M blue masking tape for sharp line masking on the fuselage and for canopy frames. I sometimes suppliment this with liquid mask for canopy frames. The exception is for NMF or Natural Metal Finish. For NMF I use 3M post-it-notes, they are low tack and come in useful sizes. On a final note about canopies. I'm getting ready to try a product called Parafilm. It was originally developed for the lab industry but modelers have learned it makes an excellent masking agent for canopies. Oh by the way don't cut the masking tape on the model or you will leave visable lines on your finished paint job. The exception would be where a raised detail is being masked(I.E. a canopy frame). Well these are of course my thoughts on these questions and others may have different approaches that yield similar results. Happy modeling and don't hesitate to ask for additional help.