Each of those are worth 20 points to the Gamerscore. Another secret achievement is ‘Complet-ality’ where we need to ”perform 1 of each type of “-ality”.
The full roster for Mortal Kombat is unlikely to complete anytime soon as DLC can add any number of fresh faces into the mix. NetherRealms Studios is developing Mortal Kombat for Xbox 360 and PS3. iPlayWinner has the full list of leaked achievements.