Dr. Z,
I'm a current applicant for Army urology and will be finding out my match results tomorrow. Great to hear you're interested. It can be tough to find information on all the programs and even more difficult when you add the VA-DOD slots in.
The breakdown is 7 slots
2 at Walter Reed
1 at each Madigan, Brooke, and Tripler
1 at Duke (VA-DOD), intern year at Walter Reed and then PCS to Raleigh-Durham
1 at UT San Antonio (VA-DOD), intern year at Brooke
All the above programs are six years except for UTSA which is 5. If you are not in a VA-DOD slot, your program would be 2 GS years followed by 4 Uro. Duke is 1 GS, 4 Uro, 1 research. UTSA is 1 GS, 4 Uro.
In terms of "reapplying," yes you technically have to. My understanding is that it's pretty much a formality. If you do a very (and i mean very) poor job as an intern I can see them taking someone else in the slot. But it's not the sort of thing where they take 3 interns and then keep only 2.