You can test this yourself very easily with a home built manometer. I did it myself using these instructions: Manometer
Simple, easy, cheap...that's how we're suppose to roll!
Wagner does make airless sprayers that are made for do-it-yourselfers. I would strongly discourage you from using the typical consumer Wagner sprayer, but I've used their airless sprayers and they work good. If you buy one, get one that supports at least a 517 tip. Spraying primer ussually needs...
Square Eye is right on! I would certainly use TSP, because it will remove any chalky paint. It will also remove mold/mildew is mixed with bleach, but make sure the brand you use can be mixed with bleach (most can).
When spraying latex make sure you get a sprayer that supports a 621 tip size...