I used a respirator and safety glasses. It didn't make that big of a mess really. I coated the brake lines and as much steel on the sides and rear as I could find without getting too much on the exhaust or rubber items (not sure what the impact is so I thought it would be safer to just keep it off there).
The stuff kind of makes the surface look rusty which is funny. Overall this car is quite clean. The only real rust is the heads of some fasteners. Now I'd like to keep it that way. The only spot I'd like to touch up is along the passenger side rocker. I had to remove the lower rocker nuts (plastic) to get the felt cover installed and forgot to spray under that area. It would be super easy. Just remove the nuts, pry the rocker down a little and douche it along the whole rocker.
I did not do anything for the front end. I didn't do anything down the center of the car as that's where the exhaust and driveshaft is. Oh, I used something under 2 cans so that wasn't bad at all. Here are all the pics.