I used Window Maker in RH8 for years and i use it now in FC2.
The compressed source code of the latest version
is about 2.7 Mbytes. I don't think it is more that a few Mb compiled.
It's just a background with 2-3 buttons(one for xterm, one for configuring Window Maker), it's more like an interface for graphical programs, that a complete desktop ( it does not have a file manger but it is compatible with KDE/GNOME).
right click will give you a menu with programs to trigger, in the latest version the menu has firefox and openoffice on it , but anyway you can configure this by just editing a simple text file), but you can trigger any program with the run command or from the xterm.
Actually i'm posting this using firefox on WM. people who use WM actually add wmapplets, small programs in the size of a wm button who do things (show time, date, weather, play cd's). Cool applets (just my opinion) is one for mounting your cd-roms, and another one for with 9 buttons for triggering 27 programs (one for eatch mouse button) tottaly configurable. If you are interested I may find the URL for you.
I've never used RH9 but how different can it be from red-hat 8.
Anyway if u don't use something u can't deside, for me WM may be very cool, but you may not like it.