Hello people, at the risk of annoying some of you with my continuance of questions regarding the use of flash for an event I will be shooting next month, I beg of you, your indulgence as I sort this out, which leads me to yet another question regarding using flash photography in a rather large banquet room. I was just informed by the director of the facility I will be shooting at that the lights, instead of being up in the ceiling, will in fact be coming up from the floor, and, that they will not be all that bright leading me to believe the room will have a somewhat subdued dim look. So that being said, my plan was, with my Canon 5 D Mark II, flash, 600 EX-RT, lens, Tamron 24-70 f 2.8, shoot manually, shutter speed 1/40 of a second, ISO 400, and aperture 4.0, (perhaps even dropping to 3.5?). Of course if I find 400 is too low, I would then boost it higher, perhaps say to 600 or even 800 if necessary. Am I missing anything here? There also will be warming lights at the various food stations that will need to be accounted for likewise. I sincerely apologize if I sound redundant and annoying, but, am merely attempting to ensure I know what I am doing, or at best, am armed with appropriate correct settings that will allow me to successfully pull this off. Thank you for your patience with my questions.