RE: Rust under the hood.
i have used simple green to clean it. I've found that's the easiest way. Soak everything in simple green, let it sit a minute, then hose off. Then go back and hit whatevers left with a scrub brush and more simple green.
if you get a miss after washing it, you just have to pull off the spark plug wires and let them dry out. putting some dielectric grease on there should prevent the miss even if they do get wet.