[KyleGoetz]

Just to clarify, some of the things you've posted cannot be translated well without context. Is the "hall of duels" anything like the Shaolin final test?

Is "vault" in iron vault like the archway of a door or like a place you store things? Both make sense with the word "iron" in English, so I don't know which one you're asking for. And I can't tell from the context of the rest of your post.

When you chose sennin for sage ninja, did you mean "a legendary wizard"? Or did you have in mind just someone who is smart?

Streets of Konoha is "Konoha no michi." You got it reversed. "Konoha" describes "michi," so it comes first. You can also think of "no" as an apostrophe+"s." In that way, "Konoha no michi" = "Konoha's streets."

Here are what I consider correct
-Legendary four ninja ---- 四人の伝説の忍者 Yonin no densetu no ninja
-General -- it really depends on context. You could use Shôgun (I don't know how to type macrons on a Mac, only circumflexes). General MacArthur was called MacArthur-shôgun back during the occupation. Taishô also works because it can mean a full general or admiral in the military. I'm not familiar with the difference between the two, though. However, Wikipedia's "General officer" entry links to JA-Wikipedia's "Shôgun" entry. "Major" links to "shôsa"
-Do you want "platoon" ("shôtai") or "batallion" ("daitai"), because they mean different things.
-Dojo is correct. Maybe "kettouba" or "kettoukan" for "a place for duels"?

Someone else can pick up from there.

My real suggestion is that you stop doing stuff in a language you don't speak. You will inevitably make a fool of yourself. But to each his own, I suppose. I say this only because I look back at stuff I did in "Japanese" ten years ago, before I spoke the language well, and think about how much of a huge idiot I was.