It is my understanding that anything that is payed for with taxpayer money is public domain provided you don't pretend to represent the agency in question, that you give credit where credit is due and you do not use that image in a way that defames the agency in question.

In other words, you can use a picture of the space shuttle or a picture of Neil Armstron standing on the moon but you have to credit NASA and you can't do anything that defames NASA or Neil Armstrong.

So, in line with my understanding, I would say Army uniforms are fair game provided you don't pretend you or your model/subject are actually in the army.

As to the other issues. Let me tell you this:

A guy was sitting in a bar and a shady character walks up to him and asks, "Hey, buddy, do you have any naked pictures of your wife?"
The guy says, "No! Of course not!"
The hustler answers, "Do you want to buy some?"