mindgarden saidAnd I'm not sure that drywall primer/sealer would work very well if watered down for spraying.
Primer can be used just as effectively in a sprayer as a roller.
you can get primers that are specifically formulated for spraying equipment, they have less fillers and if you need to thin the primer you use a specific flow control medium.
Alpha made a good point about the effectiveness of cheap nozzles, if you are hiring the equipment to do the spraying make sure the nozzle is a good quality one AND that the compressor is powerful enough to handle the spray gun.
Also there are a couple of different types of spray guns on the market, each needs a slightly different technique to be most effective.
And for clean up, proper masking and using plastic drop sheets over doors, windows, holes will stop the paint entering areas you don't want.