as for lighting, I have used 10k and 14k and they have liked both. They are under 14k now and loving it.
If you were doing a pile with a bowl in the center (and based off observing the nems in my tank):
1: when the nem is open it should fill the bowl and not be under too much current (or it will move.) It likes a bit of current maybe right across the top, but they really don't like anything to direct that 'blows' it around.
2: At night and morning/evening, mine always retreat from the light. So, you will probably want to put a rock over an edge of the bowl, or if it is a pile of rock, it should be able to pull back into the rock for shade. Mine like to have thier food somewhere in the dark, where they can 'reach' out into the light and extend to touch the current. So, maybe think of a bowl with a 1/3 of the bowl covered with a mini lid.
I would build that and drop the nem in the bowl towards the side you want it to shelter under, and see what happens. I would think you could get it to stay there.
And again, you can gently move them with mini powerheads causing them to get annoyed. Usually if I put a mini current on them, they will reposition by the end of the day (usually just pulling their goot back more into the darkness of the rockwork.
Anyway, I'm no expert. Have had some dividing in my SPS tank for 2 years or so, and that is kind of what I do to try to protect my SPS and LPS from them. They are death to anything they fight.