[wvguy]

on the second part of your question. Spraying will give you the best result if you are good with a sprayer. I suggest testing out your spray pattern on a piece of cardboard. This way you can work the kinks out. Also thicker paints can be very tough to spray so make sure you have the proper orfice to spray it. Thinning paint down is a last resort due to the fact too much water will make your paint worthless.
Second ya just mask the window off and go to town.