I taught my children what to do in an emergency too, but I have to tell you that in the real life situation of someone actually getting lost, everybody panics. I am sure that calling my child's name was the worst thing I could have done (after all, we don't want our kids' names on their clothes, but we were yelling it out loud), but I couldn't help myself. She was taught to stay calm and go find an employee and get help, but she thought she could find us on her own. It's just human nature.
I'll do my best to answer the questions about Tottoos but I can only speak from my own experience. The customer service people were great because I asked them so many questions before and I after I got these, so you can probably get better answers from them directly, but I'm happy to tell you what I know.
I had mine printed "To reach my parents, call" and my phone number, which was actually one of the phrases cust svc recommended when I asked for suggestions for older kids. The pictures on their site look exactly like the real ones. They look like a shiny sticker that would peel right off, but once they're on they are really on until you take them off with the remover they give you.
The instructions say you should remove them after 18 hours. I contacted them to ask what would happen if they're left on longer in case my kids fell asleep in the car or something. They said that they are made like a strong medical adhesive, so it can start to irritate the skin like a Band Aid does if you leave it on too long. They are made to be hard to remove on purpose without the wipes so no unauthorized person can get them off your child.
You can see in the pictures that they are shiny, unlike the usual tattoos, and it's actually a whole decal that sticks on. They aren't really the same product as a regular temporary tattoo at all, and I guess if they are going to custom make orders with whatever we want, give us the wipes to take them off, and be there to answer questions they can't be as cheap as the ones we get in a gumball machine, although come to think of it, those cost $1 these days too!
It's really not a good idea to write on kids with markers and pens because the ink gets absorbed into their skin and who knows what that does. While the benefits of your kids having your number definitely outweigh the risks of the ink absorption, now there are ways to do it that are safer. Thank goodness for progress!