What do you do in the US Marine Corps DEP program?

I will be going to MEPS and entering the DEP at 18 or just after. I will be in the DEP until Im 19 (or just before) because I would like to be an MP and you have to be 19 (I recently turned 17) to be an MP. So what will I be doing in the DEP before Boot Camp? After Boot Camp and MP school how likely am I to be deployed overseas (or just staying in the US for a little while.)?