As for why you can't hire the pirate yet, at the beginning of the puzzle you have only the first hire available (Thief, Double Agent, Infiltrator). Only 4 hours later, the next hire becomes available (Infiltrator, Pirate, Thief)
Indeed we'd like to keep discussion about the tactical puzzles in the dedicated subforums.
Here is the topic about this specific puzzle:
viewtopic.php?f=11&t=494It already has some discussion which might help you. If not, feel free to ask further questions over there.