The answer to your question on what kind of paint to use. Get yourself a white laytex enamel 100% Acrlic GLOSS Finsh Put on at least too coats three would be better. The better your walls are painted the better reflection of light you will have. The gloss paint is for the reflection. I have been in the painting trade since 1976 trust me i think i should know:hubba: anymore paint questions just ask.
Use a good quality FLAT paint. A high gloss paint does not reflect nearly as well as flat white paint. Remember, just because something looks like it reflects well, does not mean that it does, like foil and mirrors, which are poor reflectors of light.