When I first heard of this project I thought "Well, that's insane, it will never be finished, and will surely be abandoned in six months". Glad to hear that it's making good progress! I love it when I'm wrong about stuff.
Remember that most of Emacs is written in Emacs Lisp. If you take the entire source code distribution, around 15% of it is written in C. Those 15% are of course fairly complex, however it's at least less code than you may think.
Yes. The last time I looked, it was about a million lines of elisp, and only about a hundred thousand of C. We'll have it cleaned up in no time.