Well, being Infantry, he is going to be put in some combat situations, it comes with the job unfortunately. I can't really tell you what he's facing out there, because it's different everywhere you go.
As far as the 15 month deployments, that used to be the standard, supposedly it has been reduced to 12 months, but I'm good friends and neighbors with a couple high ranking Army enlisted guys (E-8 and E-9) and they say unfortunately a lot of these guys are still getting extended beyond the 12 month mark, which means they end up staying the same amount of time as before. Expect him to be there for a year, and be happy if he gets sent home early (uninjured of course).
Young guys don't want to look "needy" so just give him some time. Once he actually gets out there and sees everyone else getting care packages and some bawling their eyes out when they get pictures of their family, he'll get you that mailing address real quick. Even the most hardened soldiers get emotional when they get a letter and photos from their family. Snacks and stuff like that are great too, but make sure you ask the post office to check the International Mail Manual for restrictions depending on the country he's in. For example, many countries don't allow beef to be sent there (which means no jerky).
Rapes? I haven't heard of any mass rape incidents, but I've been living overseas for the last 8 years. But yes, sexual assault is a problem in the military, especially in the barracks (Army apartments where the lower ranking and/or single people live). I wouldn't be too worried about him getting raped. The biggest threat to his health once he is deployed is vehicle accidents and improvised explosive devices (roadside bombs).
I haven't seen the latest figures, but last I heard just as many soldiers are injured or killed from accidents as they are enemy fire.