Touch-up Painting question

I want to touch-up all along the leading edge of my trunk (just below the rear window), as I can see the metal showing thru in many spots along the edge & even slight orange-rust in one half-inch spot.

Assuming I should sand the edge, WHAT SANDPAPER GRIT # SHOULD I USE?

Please don’t tell me I need to use primer;

I’d like to just use the dealer’s lacquer

brush-on color paint (if it’s too old & thick, I’ll have to order my color from some Web site) to protect the surface before winter comes. Also: Should I DRY or WET (with water?) sand it?

use any sandpaper you want as long as you remove all the rust…I will not tell you to use a primer, but…make sure surfaces are clean and then use your touch up paint…if it doesn’t last repeat process…

When I assault paint in a minor way, I can get by with 180 and 220. If the paint doesn’t match, you can use a different color primer under it. It is cheap and dries fast.