As for paints your wally world crafts section will probably be your least expensive with its large selection of water based acrylics which involve very easy clean-up and minimal damage to your surroundings. You can use water for clean-up and thinner. Consistency for spraying should be about like milk although you should experiment for your personal taste.
15 to 20 psi should be a good start, again experiment. As for the imperfections in the tissue, paint is not going to make them disappear.You'll have to work on your covering technique to solve that issue. When spraying try not to put on heavy coats, 7 or 8 very light coats making sure to let them dry thoroughly in between.