There is a way with the software this site is using. It seems the link to the member list has been removed. I will dig around and see if I can find it.
Seems as if the admins have removed it
Mods and/or admins would be the only ones to be able to tell the join dates.
As for your second question...
I would say around April 2006 is when this forum was created. My discovery is based upon the join date of what I believe to be the root admin account for the forum installation. (Yes, I'm a programmer / forum admin lol).
Join Date: Apr 2006