The number thing - very easy answer - because I did this topic very late in the evening - the the chance to get an answer by sms was much bigger...anyway this is my work number and a some hundred people having this number - no big problem...
And by the way dive buddys are no strangers - If you start diving you will learn very fast, that you need to dependend to someone - with this dive buddy you are establishing somekind of risk community. If someone of this dive team fails the otherone need to cover him...so if you dont have trust to others dont dive....and this is not related to an age....