Fully Tagged PDF (even for math) is in the works for LaTeX

Yes, it's excellent even if you're an advanced LaTeX user. Lyx will always let you "bug out" to the "Evil Red Text" (ERT) box and just write LaTeX if you want. I did a dissertation in Lyx that had a good bit of custom LaTeX macros, to use in math boxes, and other stuff. Indeed, you can easily *extend Lyx itself* and add support for your own macros in the menu system with just a small little text definition file - so even my own macros had Lyx support. ;)

It's an amazing tool Lyx.

There is extensive documentation, from a tutorial to a reference. Which is of course written in Lyx, so you can see exactly how it's done things. :) I.e., there is both a description of how to do something and there is the thing itself in Lyx, in the doc. ;)