Congratulations to all of you. Please, please, whatever you do, do not treat your adopted son differently from your genetic child. That may sound dumb, but I do know someone whom this happened to - well, I used to, he disappeared after stealing some stuff from us.
I don't ever remember being told I was adopted (both my sis & I were), it was something I always knew. Apparently mum used to read us stories & would throw it into the mix - we thought it was the norm :) Now it gets confusing if we're talking about families - me talking about my sis's brothers (full brothers) and then about my half sis & brothers (whom I don't have contact with any more - my choice).
Open adoptions (from a closed adoption perspective) are cool.
Just remember to tell your boy that he was chosen.
Remember to save for the next bike now - wahoo, two riding buddies :)