First question, why would you mix two materials that were not made to be mixed together?

There is absolutely no reason to mix drywall compound and paint together. Instead, thin the compound with water, as is recommended by the label, to your desired consistency. Apply with your roller of choice, and allow to fully dry. Apply two coats of a good quality primer, such as Zinnser Bull's Eye 123 (blue label ), followed with two coats of your paint of choice. This technique will produce the results you are looking for.