I have used it... When I flat paneled the bed of my truck, and did not paint in time... Now you can just spray out of can with no problem, but I green padded mine and then sprayed.. Worked well till I sold the truck. Good luck
Never have - I electrolyze my rusty stuff, and if it's fracture-critical bake it afterwards. If it's a phosphate-based coating (sounds like it is), then it should be fine, just remember it may not be as long lived as some other coatings...