Well, I made myself intolerant by drinking too much. I don't know if that makes me `medically unable' to drink it, and I can drink a little occasionally, but more than that makes me feel ill.

I've not read the not-so-short guide as such, I just use it for reference as I go along (my method for learning latex having been: nick someone else's headers, get started, off we go!). It has a good index and is sometimes more helpful than googling. It has good tables of symbols, arrows, etc. Oh and if you haven't learnt xy-pic yet, it gets you going on that, though sadly doesn't tell you how to move arrows to the side a bit (so you can have one either direction; I just learnt how to do this; very pretty).