It may or may not be possible to train such that text to speech can be understood faster than reading visually (I've only heard extremely vague anecdotes on this, but it'd be interesting to test).

I don't think this is likely. Standard human speech is about 150 wpm, and while people can get up to listening to at 2-3 times that, it takes significant practice. I get the impression that many more people can read at 300 wpm than can listen at 300 wpm, and so on up the scale.

Listening is also very unforgiving to attention lapses or sections that deserve careful thought, whereas when reading normally it is easy to pause or 'rewind.'

For future reference, how does LW article formatting work, and what is standard?

My experience has been that composing articles on the "create new article" page leads to standard formatting, and that if you copy text in from another source you need to be careful to scrub it of formatting first. (One way that may work for that is to paste it into the html source, but that can lead to other problems. Copying it into a text file editor like notepad seems like a better approach.)