I'd skip the cool whites entirely, they are predominantly 450nm blue with just enough 510nm (green) to 600nm (orange) to give them a cold blue/white appearance. The light produced by cool white LEDs has a low CRI, meaning it looks unnatural, and many users are dissatisfied with their appearance.
Neutral or warm whites have a higher CRI and appear more natural, this is because they supply more of the visible spectrum. This includes red, and even deep red in the case of warm whites. These LEDs will produce less blue than a cool white but that is east to compensate for with the use of a couple more emitters in the blue portion of the spectrum.
Photosynthesis in corals requires adequate energy in a few portions of the spectrum. It's important to provide light in the wavelengths commonly referred to as "violet,'' ''royal blue/indigo,'' ''blue'' and ''red.'' ''Green,'' ''yellow'' and ''orange'' will make things look nice to the human eye but relatively few pigments are able to utilize these wavelengths for photosynthesis.
You should be planning to use somewhere in the neighborhood of 36 to 40 emitters for your build. I would suggest splitting that roughly into thirds, one third white, one third royal blue and up to one third "other.'' I would further split up the ''other'' category as roughly half violet, preferably in the 410-425nm range, a few blue (460-485nm) and/or cyan (485-510nm) and maybe a deep red (>640nm) or two. Green is optional as it is of little use in photosynthesis' I'd skip it because white LEDs already provide a ton of green spectrum.
As I already mentioned, warm whites supply some deep red, if you include a few warm whites you can probably skip the deep red LEDs. If you go with neutral whites you should probably add a couple deep red emitters and if you stick with cool whites you should consider adding a couple orange/reds (~600nm) as well.
Cree makes good LEDs and they are the most recognised brand in the hobby. This does not mean that they are the only good LED on the market, nor does it make them the best on the market. I've used Cree, Philips and Epi and each has it's pro's and con's. Epi makes a good violet, something Cree and Philips don't offer. The downside is that they max out at 700mA and 3.6v making them a 2.5W LED, not a full 3W emitter. For royal blue, the XT-E is a good choice, as is the Philips Luxeon. I used a combination of the two in my last build to get a broader spectrum. The Luxeon peaks at 440-450nm, the XT-E at 450-465, both are beneficial. For whites, the Luxeons are hard to beat, stick with the 5000K neutral white (85 CRI) and the 2700K warm white (95 CRI), they are the best on the market.
For your 9" height 85-90 degree optics will be fine, 60 degree will work above 10" or so. Drivers are a whole another issue. LED selection and quantity will have a lot to do with it, as will the method(s) you use to control your fixture. You mention knobs so I suspect you plan to start off dimming your LEDs manually, will there be a controller in your future?
