Anybody with a cjo should really go to the facebook united pilot newhire half wingers group like many have suggested. You can privately ask questions or seek out advice from a very diverse group. Once you are onboard the union PDR is great for answering the hard questions, the forums are for ****ing off people with no sense of humor, and facebook is a toss up of misinformation and the right answer.
Taking mil leave in your first year isn't a big deal. It might not be something you want to openly disclose during the interview but that might be a better question for a prep company
It may delay your probationary year as there are hour requirements and month calculations. Probation isn't a big deal but it does bite the random person. I have a feeling the story above has a lot more to it than what it appears at face value.