Thanks to everyone for helpful /msgs and reply. It turns out that there aren't really answers to either question: the many-files nature of smil is a design feature intended to keep it agnostic about source formats, and while you can in theory supply data in the inline link format:

none of the players yet support it.

and the answer to question two, thanks to crazy, turned out to be explorer being dumb about mime-types. sorry for wasting your time with that one.

this post is a bit redundant, i know, but i wanted to close the thread and leave something for later explorers. must write a howto if i survive this.