Gentoo for its strong community.
Yeah, I don't think that RH9 uses the KDE login manager (KDM) by default, so changing the settings in the KDE control centre wont have any effect. If you want your system to use the KDM login manager rather than the GDM one, you'll need to edit the file /etc/rc.conf. Change the line which says: [code:1]DISPLAYMANAGER=gdm[/code:1] to [code:1]DISPLAYMANAGER=kdm[/code:1]
Same answer as http://www.kde-forum.org/viewtopic.php?t=2872. Have you set the levels using kmix?
Have you tried editing your ~/.gtkrc-2.0 file? Mine simply has one line: gtk-font-name = "Luxi Sans 12" The Firefox fonts are exactly the same as my other KDE apps (default font Luxi Sans).