To Paint, or Not to Paint.........

Ok......so I painted my kitchen all white, back in July, and stenciled Mickey Mouse heads for my border. The problem? The 'old' paint on my ceiling is chipping away and desperatly needs painted. I bought red paint for the ceiling, thinking that it wouuld bring out some color in the kitchen. Well....with my family coming in this week, I really want it to look good. But...what is the best way to paint a ceiling? Do I need to scrape off all the chipped paint? Do I need a primer? Is a roller too messy? Has anyone out there done this before? It will prbably take a few coats, but was interested in some thoughts........ Thanks.