Very nice. Black & White Maxes are awesome.
I would try and get it as high as possible unless you have like 350+ PAR in the sand. Some people will tell you that I am crazy about them needing that much light, but in actuality, I like to get them more like 500+. They can do Ok with less, but they can thrive with more. Even if they are just doing "Ok," they are less likely to fight off any issues that come with parasites or water parameters.
You can remove that rock with a sharp knife by cutting the "cords." If you tip the rock ever-so-slightly to one side, you can slowly cut them away. This is no issue to the clam unless you tear the rock off. It should reattach in a day or two.