[texhax] Tex and Latex

[Karl Berry]

    I've just read a Tex and a Latex book. In latex, there's fonts from
    small to Huge. What command in plain Tex gives those font sizes?

None.  Plain TeX does not have any text font support comparable to LaTeX.
It just defines the basic commands \rm, \it, and so on, to use 10pt
fonts.  Anything else you have to build yourself.

    I'm writing a users/service manual and it doesn't fit into the
    latex classes of book or report well. Is latex designed to be
    easily adjusted so that i can change all the book-class numbering
    and heading conventions for chapters/sections?

I would hope so, but I am pretty ignorant of LaTeX hacking.  There are
assorted documents floating around, an incomplete list is at
http://tug.org/interest.html#doc.  Perhaps others on the list will be
able to give more specific pointers.

Happy formatting,
Karl