I know just how you feel, setting up a marine tank and finding out you can't have coral!!
I'll ask Colin to correct me if im wrong but i believe that while some corals still sting them and others may be too delicate, a cuttlefish can be kept in a reef tank if you do some research and only choose hardy, non-aggressive corals. I guess this is because they dont 'crawl' as much. Then again i have also heard that cuttlefish like to redecorate.
Of course if you have your mind set on an octopus then i dunno - perhaps there are some corals which are safe for an octopus too? About the lighting, i believe if you provide adequate hiding space, the light won't overly concern the cephalopod. Just dont turn them on too quickly!!!
Hope this helps
sam