1. Nobody has written the LaTeX -> MathML code yet, and I've been too lazy. Anyone who is interested in doing this should get in touch.
Well, I'd certainly be "interested". I use mathematics *a lot* in my writing. Presumably modifying a large program like Pandoc is intractably difficult though?
Just write a separate library that parses LaTeX input and returns MathML output. Pandoc could then use this library. So you wouldn't need to know anything about pandoc's internals. Just write a function teXMathToMathML :: String -> String. This would be a great contribution! You could get a head start by looking at the LaTeXMathML.js code.
It strikes me that perhaps using LaTeX to enter mathematical markup is rather against the spirit of Markdown. Surely there should be an option to include raw LaTeX, but a more "natural" encoding that covers "most" mathematics would be nice also. Of course, that means somebody has to design it first...
I think it makes good sense to use LaTeX, which is already designed to be natural but flexible, and is already known by most mathematicians. My guess is that in designing a more natural format, one would eventually reinvent something like LaTeX... John