I have found that while folks are well intentioned on commenting on this sort of thing, everyone's needs are different, so some info might not be accurate for you. Some years back I read a bunch of online stuff that said camera and purse restrictions were lifted for Mammoth Caves. But the web site said they were restricted. I e-mailed and learned that they were indeed restricted from being brought into the caves.
That said the NPS website is the best resource for this kind of stuff. You can also email or call the NPS office at the Grand Canyon with additional questions. I've always got fast responses to questions. Don't be shy about being very specific about your situation so that you don't find yourself in hot water later.
Hope this works out for you, its sounds like a fantastic trip.