I'm studying for the MCAD and using Kalani's books. I find them helpful. Also, contact a test center like New Horizons and ask them for some keys to msmeasureup.com (they give them away usually). There you can take practice tests in study/cert/adaptive
As far as taking classes from a test center, I personally do not recommend it. They are very expensive and I don't feel they saved me any time or studying.
The salary issue really does depend on the employer. I was able to negotiate an increase in salary upon completion of my MCAD based on the statistics in the "Profit and Loss" article at mcpmag.com.