1 A cutesy abbreviation of "-chan".

2 I wondered if it might be something like that. I had a hard time believing it, with a junior member of the military using it for a senior officer he doesn't even know all that well. Sounds like a serious case of insubordination.

3 I suppose we could hand-wave it by saying that politeness conventions are different in Midchild than on Earth, couldn't we?

4 This is seen in modern school setting in anime a lot, e.g. students of Yabe's class in Mitsudomoe call him "Yabe-cchi". He even appears startled and dispirited the first couple of times it happens. I would agree that in the military that seems rather out of place, but if the object of it does not come hard down on the perps right away, it is likely to stick.

5 It's definitely a cutesy diminutive (not "little girl" cutesy so much as "the person saying this is being very familiar and a little whimsical").

I'll check the scene you're talking about in Strikers. It would be utterly inappropriate for a conventional military setting; on the other hand, no conventional military setting has captains not old enough to drink!

6 A Google image search for "Yunocchi" tells you everything you need to know about what the -chi honorific means and how it is used.

7 Come to think of it, don't the kids in Shingu call their teacher Yamamoto "Yama-chi"? (Or was it something else?)

8 No, wait, they called him "Yama-chu", right? Presumably it's the same kind of thing, though.

9 I think I remember the line as 'Yagami-chuui'.  I translated the show but it was so long ago now I'd be hard pressed to remember.
I can tell you with absolute certainty that it wasn't the 'chi' dimunitive though.

10 Just rewatched the scene. It sure -sounded- like "Yagami-chi" (though not quite the same sound as "Yagamicchi", which would be the diminutive). Dunno, honestly. I'm tempted to chalk it up to formal Japanese military speech, which has plenty of nooks and crannies that I've never been exposed to.

Can't be "-chuui", anyway, she was a captain, not a lieutenant.

11

There are a lot of ways in which the Midchild military doesn't really match what we know. For instance, when Caro and Erio first meet Ginga, they salute.

Ginga is a sergeant, and you  don't salute non-coms in our military. And that's not the only time we see that: in the first episode, Subaru and Tia salute Rein, whose nominal rank is Sergeant Major, so they say. That's a pretty high rank for a noncom, but even so.

Another is the whole rank structure of the 6th Division. Tia, Subaru, Caro, and Erio are the "forwards", the lowest ranked part of the strike force, which also consists of Nanoha, Fate, Vita, Signum, and Hayate. As such, they de facto outrank everyone else in the unit, and are shown acting like they're in command, despite the fact that all four of them hold the rank of "private".

12 What I meant was, "At certain times they're shown being in command, despite being of such lowly rank." For instance, After the attack on their HQ, Tia is shown coordinating the cleanup and investigation, until she's relieved by Fate, who sends her to the hospital.

13 In Red/Soviet/Russian army, you salute everyone who outranks you, and they are supposed to return it (unless standing orders are in effect to cancel salute). The only exception is, you never salute without a headgear.