I have used the new Behr ultra paints , they are great, the built in primer really does work, I have gone from dark existing colors to lighter shades, and have experienced excellent results.
Generally I would apply a primer like kilz or something of that nature, then apply at least two coats of wall color, but the Behr range of color and built in primer has saved me many hours of work.I trust this information shall be of benefit to you, and good luck with your project.
The Behr all in one paint is more expensive than regular paint, but it's worth the Additional cost in the time it saves on the painting, I am a contractor and always seeking ways to speed up the work process.
Paul M