D.H.
It has been many years since I have gone to Nationals for dance competition, but I do remember some things. First, the cell phones not being allowed is to keep the kids focused on competing and workshops. We have the problem of kids in dance class constantly checking their phone to see if their BF texted them back. It disrupts concentration and their focus isn't on what it should be. As long as the chaperone give the parents their cell phone number and that chaperone keeps their phone charged there is no problem. We do that for church camp too. Just remember years ago there were no cell phone and we were just fine leaving for competition or camp without them.
As the chaperone and leader in charge of several kiddos I commend you on wanting to contact the parents. Good for you. You will need to get all contact numbers for them. Work, neighbor, mom and dad, brother and sister, grandma and grandpa. Just in case something does happen and you cannot get a hold of parents or family. Then find out if any of the kids has medical conditions...like asthma, ADHD, or something they need medication for. The studio should already know this and have this info for you, however it is good coming from the actual parent and they can always give you more info than the studio can. Like what to look for if an attack starts. And it will be good that the parents will learn about who is watching their child. Make sure you give them your numer also. Then for your room, bring snacks. Not a ton, but some. I remember going back to the room after dancing all day and being very hungry. Crackers, cheese its, and such. Not cookies and stuff. You don't want the kid who cannot control herself eat a whole box of cookies and be puking all night. (been there, done that)
I love the Visa card idea...didn't have that in my day. The only thing is, you should have them and not the kids. This way they don't get lost. I've lost money before and it is nerve racking even for a kid. So if you get your parents to send the card with the child (their name on it) and you keep track of them so they are not stolen or lost. These kids my seem honest, but trust me there will be one kid that will have a history the studio doesn't know about. Kids act one way at dance and another when not at dance. So if you are willing to hold on to those cards that would be great. It will also keep them from over spending too.
At the competition there will be booths to buy suveniers (sp), so make sure that at least your child has $$ to purchase a shirt or something. I remember buying entire outfits and cups and such. Won't be cheap either. But something they will cherish. You could mention that to your parents too. If they want to send seperate $$ for that.
One more thing...make sure everything is labeled, including underwear! Yes, underwear. A lot of these girls are the same size and purchase their underwear at the same place and believe me they will get mixed up. These kids will not be neat when they are away from home. It is like a new freedom for them. So you may want to be a room nazi and make them keep their clean clothes in their suitcase and dirty clothes in a bag (which I would bring a garbage bag for each girl in your room). That way they know what they have clean and don't wear the same pair of underwear twice, or tights for that matter....eww. ;0)
I hope this helps some. Like I said earlier, it has been a while since I've done dance competition, but I have done church camp and church trips...the studio where I teach doesn't compete, so I don't have to worry about that anymore, but do miss it!!
Good luck and God Bless and Have Fun!!