To begin with, have you read any ordnance literature of the period, in its' original form? O.M. 22 is excellent, even though it dates from the trapdoor period. Same workplace, methods and people. Failing that, have you read any/all of the work(s) on the Krag, by Mallory, Brophy, or Poyer?

(1) I respectfully disagree, strongly. The "short perod of manufacture" had absolutely NOTHING to do with it. There WAS a lot of flip-flopping on SOME things - particularly sights, but, AFAIK, the ORIGINAL receiver finish was case-hardened in oil, period. This was not a durable finish, at all, and many, if not most, were ultimately re-browned - some possibly more than once. The silvery "plating" to which you refer is, IMHO, simply the remains of those processes, and NOT any sort of "added" material (as in real plating).

The reason that the finish is not unifrom from part to part (such as receiver to barrel) is that some parts were hardened, and some were not - it has nothing to do with indecision by the makers. 

It (the silvery look) is quite common and well-understood by the Krag collecting community. Your touch-up bluing is not recommended, it will never "look right", and will lower the value. To do a "modern" reblue, would be, in my eyes, TOTALLY wrong, unless the arm has already been "sporterized".  Remember, you do not "own" your guns - you are simply a caretaker for generations to follow.

(2) I agree, 100%

(3) A bit redundant, but again I agree.

Well, that's MY two cents, from the vantage point of 40 years of collecting. I may post some specific pictures, I may not - but you can always check out my website. 70210, a Boxer Rebellion carbine, illustrates the silvery look. 200722, an 1898 rifle, IS nearly new, but there is no receiver close-up. A "new" 1899 carbine - 357288 - is not (yet) shown - its' receiver has about 95% original black-oil finish. Perhaps I'll add a closeup, when I add the arm to the album. A photo session is not an easy undertaking for me.