1) Because you've now been a member for 30 days. :P
2) Once a 'good' list word hasn't been answered in the last 30 days, it is then added to the 'oblivion' list, and stays there until you have answered it again.
Practice mode throws 'oblivion' words at you automatically, so there's no real need to manually click on the list and go through them all... though you could clear them that way if you wanted. :)