MP's do their training at Ft. Leonard Wood, MO. I can't describe what their daily life is because I'm not one. Anywhere you are stationed can turn hostile, just some are more prone to it.
Just a heads up 31b is going to be a difficult MOS to catch unless your 1.lucky and catch one open or 2. wait for one to open. I'm not going to sit here and tell you that you wont get it I just want you to know that it could mean a long wait if you are deadset on getting this MOS. If your wanting to enlist ASAP then I would do some research and take a list of 5-10 MOS's that you would like or wouldn't mind when you go so you stand more of a chance of getting one you want. But like I said if you are deadset on 31b you should prepare yourself for a wait if you can't get one reserved.
Hope this helps, good luck!