Re: My Rustoleum paint Job. + new seats
As for the runs, you can lightly sand them down......and I mean lightly. Nothing too coarse, perhaps carefully on the run itself with 600 grit just to take most of the height off it. Then a 1000 grit. Then carefully use the typical rubbing compound and buff it to match the surrounding area. Black is difficult as it really shows imperfections....where white doesn't. Worst case scenario is you go too deep and have to touch up with some more paint. Then you can simply use some light compound to blend it it on the edges. It depends on how bad the runs are. If they are barely noticeable and out of the way, you might just decide to live with them! If you're unsure about your skills in making it match, you can always carefully sand the runs off and then tape off the area for another stripe or other cosmetic addition to cover it up! Sometimes that's easier for beginners.
Orange peel is likely due to contaminants on the surface, such as wax, grease, oil. I wouldn't sand the orange peel unless you are ready to go all the way down to the surface.
I spent 3 months doing a 19 foot ski boat to perfection about a decade ago. I wish I hadn't. I got so paranoid about anything that could possibly scratch it. Functionality is best I think......if the boat is not for show, but for playing, skiing, fishing, etc.....you'll be the happiest with a 'good' paint job, not a perfect one. That way you won't freak out when you hit that little twig floating in the water, afraid you may have scratched the hull