'96 legacy LS (auto)

Im looking at a 96 LS right now and its pretty cheap but there are a few things that need to be done here and there. Im taking it to a mechanic friend of mine tomorrow just to get some diagnostics done. 1.It does need a new caliper(eh) 2.The owner described it as needing a half axle boot. Excuse how uneducated I might seem but im not entirely sure what that would mean and 3rd the AWD has a problem he said it was the transfer case but subes dont have those so im not sure. Any thoughts or advice for me would be great! I do have some money to put into it and Im willing as well! Thanks in advance for any help/advice! My apologies on the limited knowledge Ill know more soon.