help choosing the type and brand of paint to use for my kitchen

[scotchnrocks]

I ended up going with eggshell over the semi-gloss. The semi-gloss was a little much, but I wanted something more than completely flat. I went top of the line too (~45/gal) since it wasn't much more and I only need a gallon. Got a nice Purdy brush too. I plan on having to do a few coats, so I might not get new pics until tomorrow. How long will it take me to paint ~100sf with a 4" brush?

Also I don't feel like messing with all the primer crap. Is it ok to just paint over the existing paint after cleaning the surface? Especially considering I'll be doing a few coats, I don't think it matters, could be wrong though.