I'll add some clarity here on what is expected of candidates for IODP 1.1 (Infantry Officer Development period 1.1, "Dismounted Platoon Commander")
There are five basic modules:
1st is Weapons. Here you will cover the platoon weapons and fire them. Important here is to remember the characteristics of them, as you will be expected to know this more than the stoppage drills, as an example (though handling is also key, given that you will be operating them throughout the course). What I mean is that when you are setting up your guns, etc, you'll have to explain the why things are set where they are. For example: "Sir, the MG is here such that it can provide grazing fire across the front of 6 platoon to our left. It is in defilade to the probably enemy approaches to our front, and is sited in conjunction with 4 platoon's MG further in depth. It has mutual protection from 2 section to the front, and its arcs are interlocked with the LMGs from 2 section and those of 6 platoon." Stuff like that.
Next is defensive operations. Here you will also begin to implement the estimate. Now, I don't teach the course, but I have attended a few PRBs in which candidates have said "I didn't have time to do an estimate, so I just wrote my orders." BUNK. Do your estimate right, and it completes your orders for you. Anyway, in a static location, the defensive is the place to begin to understand the process of completing an estimate.
Third is offensive operations. Here you will conduct hasty estimates and lead hasty attacks. You will build further on the skills you learned in the first two modules.
Fourth is patrolling. As mentioned, there will be more patrols in the upcoming courses (it's a scheduling thing).
Finally, you have "full spectrum operations". This part used to be pretty well COE stuff. It will still have that, but it will also remember that combat is within the full spectrum of operations. So, in here, expect to advance to contact, dig in, patrol etc ad nauseum. Following that, your environment may get more permissive.
One last point. The exercises will be long. Expect to deploy for 8-10 straight days per ex, four (or so) in total.
Now, how to prepare? Get in shape. Start now. The kind of shape you need is endurance. Be able to walk for ~48 km over 2-3 days carrying ~100 lbs of "stuff". And be able to lead. The mind will go when you're tired, so you best start NOW by being able to last AND FUNCTION in such an environment.
How to do that? Start with building up endurance by running. Go for distance not for speed. EG: if it takes you an hour to run 10 km, then that's fine. Just run 2-3 times a week, for a total of ~50 km/week. Dont' forget to build muscle by doing other training as well (swimming, weights, etc).
As for the failure rate, it was relatively low since last June. The RTU rate, however, is high (+50%). Most are due to injuries that are a direct result of poor physical fitness. Some were just dumb rotten luck (eg: twisted ankles, etc). The school can accomodate some things, but one thing to remember is this: there is no "magic timeline" to be absent from training, eg: 48 hours and you're gone. As the TP states (and I paraphrase) "The Commandant can remove a candidate from the course for missing any training". The key is ANY training. You see, the idea is not just to do an assessed task and then off to the MIR. One component to each PO (Performance Objective) is to participate in the entire exercise. Troops overseas are routinely away from FOBs, etc, for lengths of time longer than your exercises, carrying similar weight loads and in extreme weather. So the school will NOT graduate anyone who cannot last.
I hope this helps.