The rules say
>> The only stipulation is that you may not make all of your picks in the same round.
without specifying a tournament so I guess it applies for all tournaments no matter MM, Masters or GS.
As for the pick - I scratch the last one from the set. I had a case like that before and Shaun said I should ask the player but if the player doesn't choose which pick is to be deleted to scratch the last one as invalid.