Well, first off, CONGRATS on choosing your dress! We want to see pictures!!!
I know I've seen millions of pics of beach brides w/the train out. I plan to do it, and I don't think you will need to worry about dragging piles of sand, unless for some reason your train is really heavy.
Regarding footwear, I plan to go barefoot for our ceremony on the beach & slip shoes on for the reception. If you have your dressed hemmed properly, you shouldn't have to worry about your footwear (or lack thereof) showing in the pics, unless you want it to.