When you call up to order the paint ask tell them what you want to do with the paint.
They are very helpfull.
Also, when you use the paint stir it up good then pour some into a glass jar or hard plastic jar or something.
You don't want to dip the paint brush in the paint can.
This stuff is very strong and will eat through a soft plastic cup.
If the paint is not flaky you can paint right over the rust. If it's loose or flaky wire brush it first.
They will advise you to buy a bottle of marine clean from them.
It's very good stuff it removes all of the dirt and grease.
Most important thing is to make sure surface your going to paint is dry.
Good luck,
Schoon