Dave, I'd definitely use a monopod for that lens. I use one with my 200-400mm Nikkor. It'll do a couple of things. First, your images will be sharper. Second, you'll be able to take more images since you won't be nearly as tired at the end of the day. I suspect that you'll be quite tired hefting that huge lens around all day, even with your size, without some kind of camera support.
As someone else mentioned, for the "air" part of the airshow, I usually use manual exposure. The exposure difference between a shiny P-51 and a dark Spitfire would be many clicks of the compensation wheel. Set the exposure, then check once in a while.
For propeller aircraft, the shutter speed should be less than about 1/160th second. Otherwise, you'll stop the prop resulting in an unnatural looking airplane. For jets, I set use the widest aperture the lens has. That will allow the fastest shutter speed possible.
When shooting ground displays, patience is a virtue. I've often waited many minutes for people to get out of the way for a shot. Be ready, though, because an opening never lasts more than a second or two at a busy show.