See the current "pitcher vs. catcher" thread for an example of a coach inviting a player to a camp.
If you get a camp invite and are not sure, you can reply to the coach (email, or phone) and say that the date of the camp is not possible for you, but you'd like to get in front of the coach some other way or time. You'll then find out how personal the first email was.
The age rules for contact simply mean that if a coach is really interested in a kid who is below the allowed contact age, he will contact the travel coach to set up a call or camp. That's also how you'll know.