if walking boots keep ya feet dry, take them, if not wellies
tripod or beanbag most people used tripod, but getting down and dirty on the sand is a little awkward and as the 100-400 has IS i handheld most of the day
Matt used flash to kill some shadows in some of his, depends on weather ion day i guess
I took 240 last time, could have taken loads more though
take a plastic bag big enough to wrap the camera and lens in, clear if poss, this is just in case its windy and the sand and spray are getting whipped about