Flash cards are the only way for the vocab, you will have a stack of about 500 words to go through, but will definetly help your score (I preped in 2 weeks), and then you flush it just as fast.
If anything, practice the math test at least a few times, if only to get the timing down... Because of the question selection (next question based on how well you are doing), you have to focus on the first questions. You also have to make sure you answer all the questions, if only to "guess" an answer... the worse questions to miss are the first one, the best ones to miss are the last ones, but do not leave any blank, that is worse.
Doesn't matter, something that interests you. A lot of the satellites offices only offer a few specializations, typically safety is avaiable I think... I tried to work a human factors specilization, but Chuck-Town did not have teachers to teach enough of those classes, a big problem if you PCS before finishing. Choose a "safe" route...