I finally got off my butt and re-arranged my shed so I can use it as something of a paint booth, so I now effectively have the space to repaint the engine cover and louvers.

I've got to repair some large scratches in the louvers- I've got some Bondo gazing/spot putty to repair those, and have some more 'real' Bondo to fill in the holes from the old 3rd brake light.

Obviously, they will need to be cleaned heavily- what works best for paint prep?

I've seen it said to initially sand with 320 and then wet with 400, is that right?

Is it really necessary to go over them with a primer first?

I've got SEM Trim Black to repaint them with... I'll make an attempt at getting the texture of the louvers back (think Dave said to spray from further away so the paint is partially drying before hitting the louvers), but if it doesn't work I'll deal with having the smooth black.

Thanks!