A good way to have the live rock in the sump is to have it in the intake area with very high flow, should eliminate the detritus, you may want to convert it to smaller pieces to allow better flow. If it sits in a lower flow area, it will end up being a trap. Although, I did not implement a live rock area in my sump this go round, I did add some rubble for hiding places for microfauna.
Those lights look awesome Herbie, I may eventually grab one. I'm using a 5k version from Menard's (was roughly $30 bucks) and the samples of various macros I have are multiplying super fast. I read so many different theories on fuge lighting, so I just went and spent 35 bucks on the bulb and fixture to see how it works, so far so good!