Stick with a 12 hour (i.e. tropical) lighting scedule. That includes sunrise/sunset time, which I ususally do in 30-60 minutes each. Just a short time at peak lighting levels.
After that adjustment, I would start by getting a light meter to help you assess your light's intensity. You may decide no further changes are needed...but I would not keep guessing on this front.
You can start out with a $free lux meter app for your smartphone. It uses the camera's light meter and a little software trickery to generate a lux number. There are lots of free ones - someone here on R2R was even working on their own app - and people have been getting usable results.
That said, while the app is installing, go order a $15 (delivered) handheld lux meter from your favorite major reseller. The "LX-1010B" is the basic model I think most people get and it works well. Much better than the app AND (at $15) safer to use around salt water than your phone!!!
As for your lighting targets?
There's a wide range of what's "theoretically" acceptable to corals - they are VERY adaptable. Keep in mind though that more light isn't better.
Anywhere from around 20,000 lux up to around 80,000 lux seems good for many corals.
Right in the middle of that range - around 30,000-50,000 lux - seems like a sweeet spot and is where lots of commercial fixtures seem to max out at "100%".
However, unless you're starting a new tank from frags (which are ultimately adaptable to new light conditions), it always gets down to the specifics of the corals you are keeping and your situation.
For example, if you're transitioning an established tank to a new light, then your main goal is not some theoretical number. Instead, you want to match the actual intensity of the old tank as close as you can.
A simple light meter makes it pretty easy!
For color, you can pretty much set what you think looks nice and be OK with it. Correct intensity is much more important than color to your coral inhabitants.
