Some of our submodules are 20 times bigger than the Linux kernel and there is no way to subdivide them more than that. Our source base really is that big.
Let me guess... that's Windows Vista
So: no, it's not stable. It's a nightly build.
Yes, it's running reasonably stable for me. But no, it's not officially marked as being stable. I don't care, your mileage may vary.
Neither of the links you provided mention the term "minefield."
Yes, that's true, why should they? The first one is the Mozilla Trademark Policy. The whole point of Minefield is that it is not handled as such. The second link explains how to obtain the source code for what "is used for the development of Firefox"
The point of my last post was that official versions are also available as Minefield (or IceWeasel and others).
BLISS is ignorance.