No, your settings will be fine even if you let's say remove your old RPM packages first (rpm -e <Packagename>.i386.rpm). This is because your KDE settings are kept in a folder in your home directory called 'Desktop' (as well as in some .files) while KDE itself is normally installed into a directory available system wide like /opt/kde.
But of course, it is always advisable to backup. Other than your personal config files, backing up $KDEDIR/share/config seems to be a good idea, too.
If you have enough space, move /opt/kde to /opt/ke10, say, and install onto /opt/kde11. Do the same with $HOME/.kde and also back up $HOME/Desktop. Use symbolic links /opt/kde and $HOME/.kde to get the installation prefix right without changing the environment variables, and also to switch between KDE 1.0 and 1.1. Do the same with Qt.