This is a late post and I'm not sure anybody is evening going to see this, but what the hey, it looks like good fun. First of all, let me make clear, I am not CI. My experience on this post comes from my background as a CI Team sergeant. The unit I was assigned to was an Army CI reserve unit. The old designator for the enlisteds were 97B, so that was my duty MOS. The focus of activities were always mission focused. I'm not saying that you should go reserve, this is just an illustration of what types of duties and activities you will do as a CI agent by describing what this unit was responsible for. Being an old recruiter, I'm going to keep the language simple for people who do not have an Army background, especially for those wanting to "switch" services and want to see what's out there. The unit I belonged to had several different teams, all with a specific type of operational capability. The first one I'm going to cover is the CI Investigative Team. This team was responsible for doing pesonnel investigations, mainly for security clearances. I saw a lot of training at the unit to support this mission, as well as anecdotal evidence from our deployed soldiers. One thing that's important about this particular activity is that we don't do investigations or intelligence investigations of U.S. citizens except under very strict exceptions. This team also does investigitations, but not criminal investigations. You could say, they investigate for instances of treason. Criminial activities when discovered is turned over to CID for further action (always a close relationship with these guys). Duty uniform is usually business casual (I hated this uniform). Badge and Credentials (B&Cs) are only issued when they are needed, you don't get to carry these all the time (unlike civilian law enforcement). As mentioned in an earlier post, you carry a pistol. You are considered a federal agent, but the unit will restrict you ability to enforce law (especially off-duty) because of political reasons. And every once in a while, you get to do fun stuff like surveilance and high speed chases. What kills this job is the report writing (yes, you can expect this since you are considered law enforcement, writting is an important skill). So that's the idea with these guys.
On the tactical side, we had a couple of special operations teams. Their main mission was collecting field intelligence, meeting with snitches and the like and trying to paint a picture for the commander about what was going out there in the field. Yes, combat is a given. CI teams in the tactical missions can operate as two teams of 5 in 2 humvees, similar to MP units in the field, and as such, are fully capable combat units (the two teams actually had more firepower than a standard infantry squad). Weapons will consist of the pistol (for everybody), everybody carries rifle of some form, with select individual carrying the grenade launcher, and in my case, since I was the team sergeant, got a SAW (or because of my infantry background, who knows). B&Cs are not normally carried in these units (chances of loss of these is a big worry for commands). Stress is very high in these units, as your exposure to combat is constant, especially in enviornments like Iraq and Afghanistan where you will spend a lot of time out of the wire collecting information. Of course promotion is quick in these units.
As far as the interrogators were concerned, that was a different MOS altogether (forgot the exact desigantor for this) and we didn't have any of these with us (not normally). One thing to keep in mind. Interogation was used differently by different activities. Investigations did not use the term interrogation, we normally used the word interview. Crime investigators like CID were allowed to use interrogation techniques, I didn't see a lot of CI agent training in interrogation (though I have use some of these techniques "interviewing" people when I was a recruiter).
So, I guess the summary here is that no matter what they teach you in school, you gotta be ready to do any of this stuff, I was just lucky enough to get into a unit that had a mixed mission. No guarantee you are going to get a specific unit that does a specific thing in the CI world (unless you go SF, my suggestion). If you want to go into a purely law enforcement type of job, go CID or MPI. You James Bond types need to go apply to the CIA directly. Otherwise, "Light 'em Up".