General consensus used to be that they should be kept out of the light. During my research though, I noticed a few places stating it wasn't necessary. Like Grins said, they don't need the light to survive. Before I re-scaped it was in a slight cave and used to open up when lights went off. Since I've moved it here it opens up morning and night and sometimes during the day. So I'll let the pictures be the judge!!! (Oh and the fact I have baby ones popping up all over the tank!!!)
With regards to care, they're not that hard. You just have to target feed them every couple of days. I feed them with a mixture of mysis, krill and finely chopped mussel and try and put a piece in as many heads as possible.
I've recently been doing some more research, and although general consensus is that sun corals don't mind the light, algae loves it! Quite a few sites I've looked have stated not to keep them in striong light as it can cause algae to grow all over the coral, therefore suffocating it. I had noticed a few spots of algae on mine which were easily blasted off with a turkey baster, but since reading this info, I have decided to move it to a more sheltered area of the tank.