What, you want the User's Guide twice?
Seriously, though, we're here to get you up and running so that all you need is the User's Guide. If we tried to duplicate all of the information about all of LYX's features in here, the Tutorial would be redundant, too long, and forever out of date. All we do here is introduce things; imagine there is a ``see the User's Guide'' at the end of every section.
Unnecessary. If you're really curious about learning some of the neat tricks you can do with LATEX, you can always go get a LATEX book. There are several good ones on the market. No need to reinvent the wheel, after all...