Sounds like you've got the help you need. But just to answer. Your q's. The silver stone will cover the primer just fine. They will probably use several coats of base color before they put on the clear. Any paint will work for the guide coat. It should end up being sanded off anyway. The quicker the drying the better. Start with a med fine paper and work up to a 400 grit. Just remember, the finish paint will not fill in anything take the time and make it perfect. Use a flexible sanding block to back your sandpaper.
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