Your points 7 and 9 may conflict.
True, so we had to teach her that in an emergency/lost situation it is okay talk to strangers.
One thing I read a long time ago was to give each member a secret codeword. The child can talk to people that know the password, which the parent could give out in an emergency. I think DD1 needs to be a little bit older before we get into that.
-Blast