Hi, and welcome! To answer your question about placement of coral, we all need to know the type of coral you are refering to. As mentioned previously, you will need more than the standard lights you have. Mushrooms and possibly leathers may do ok with your lights, but other corals require much more light. Different species like different lighting levels as well as different water flow. If you have a specific coral you are interested in, by all means give us a name and we will try to help you.
For your substrate, I would reccomend getting rid of the crushed coral before you go any further. I too started with CC and changed to a DSB after my tank had cycled. I made the change on the advice I recieved here and because I could never get my nitrates to zero. Corals and other inverts are sensitive to nitrate, and this was what I wanted to keep. Since the switch, I have never tested positive for nitrates.
Keep asking questions and take it slow!
HTH,
cyn