First let me say that these are very good questions.
My answer to the second one would be similar to many others, let me just add that MO has immensely enhanced my feeling of being a member of one of the most worthy communities in the world.
Concerning the first - I think MO is similar (in a minor way) to things like ethnic entities or languages which develop according to their own metapurposes whichthat might be not known or even unreachable to people participating in their development.