Drywall is pretty much like a sponge, in my experience. I'd really use
a coat of primer -- something like "Kilz," or the like, then the color
coat. The results will be much brighter, as the primer is really
loaded with pigment. The primer not only gives better adhesion, but
since the finish coats have less pigment, usually, then you will get a
"brighter" result, which is what you are looking for. As to finish, an
"eggshell" is nice, as it can we wiped down. I use eggshell finish all
the time for things like a kitchen or bath, as they get dirt, grease,
etc., on them. I think the gloss would be excessively reflective.
Good lights will help a lot, as well.