chupacabraVS2: 1. Yes "darker" ones are ones you haven't gotten. As you said 2. The different colored "cups" are just levels. It appears that 20 achievement points and under are "bronze". 25 up to some other limit is "silver" cup, and the higher ones are "gold". (Or whatever the colors actually are) 3. You only achieve an achievement once.
(hide) If you only look at some of the discussion boards on a regular basis you can add them to your favourite boards list by going to the Board page and clicking "Add to my favourite boards". (pauloaguia) (show all tips)