Getting closer to Slick Sand Phase and have a few questions: What grit sandpaper should be used on the slick sand (between coats and on final coat). 2nd...should a 2k primer or sealer be used over the slick sand prior to laying down base coat?

And on color ....Should the door, trunk and hood hinges be painted the same color as the car or black. The door hinges on my MK III are powder coated gloss black and I kind of hate to sand them and repaint them, but I think all the hinges should be the same color. Any thoughts??

Thanks
Paul