Is the main source of pain being swollen feet then? Is the basic goal to prevent then from getting sweaty and over heated? Would you recommend switching to Flip-flops mid day for 3-4 hours?
Not so much swollen feet, but the aches and pains of standing up a lot and walking quite a few miles per day (although we try to keep walking to a minimum.) Although I walk for exercise daily, Disney is much more walking that I do normally. Its also a lot of walking slowly, stopping, standing, etc. - different than just walking for exercise.
Your feet are going to sweat, but you want to try to keep your socks from getting soaked with sweat (hence, moisture wicking socks.) Cotton socks soaked with sweat are like sandpaper after a while. A former boss of mine swears by changing socks while at the park. Other folks will rub their feet down with Body Glide or even vasoline. I prefer to powder mine with talcum baby powder. BTW, don't get corn starch. It will clump and its a great growth media for fungus. BTW, when we are eating lunch, I will also slip off my shoes to let my feet cool down.
Regarding flip flops, that's a question that only you can answer. Do you wear them a lot? Are they comfortable? Can you walk miles in them? For me, I can't wear them long because I have plantars fasciatis, so I wear my Sketchers with orthodics in them. I have read that some people will take a pair of flip flops in their park bag and either wear them on water rides or change into flip flops part way through the day.
I assume I ought be doing the ibuprofen from Day 1, then, even though the pain doesn't typically start until Day 3? Just keep ahead of it?
Yes, you want to keep ahead of any pain. Start taking them on the morning of your first day, and then take them at lunch. I do this for my feet, although I also take ibuprofin for my early onset osteoarthritis (a 40th birthday present....)
BTW, and this may sound like a weird question, but do you have a wife named Amy? If so, I met both of you in late February when you came to Alabama.