You don't see any icons for /floppy, or /cdrom because Knoppix mounts them in the root "/" directory. You will see them there. Also look at your /etc/fstab file. It will show where and how they are mounted. i.e.:

/dev/fd0 /floppy vfat defaults,user,noauto,showexec,umask=022 0 0
/dev/cdrom /cdrom iso9660 defaults,ro,user,noexec,noauto 0 0

Because of the "noauto" option in the fsab file they are not automatically mounted on boot. Remove the "noauto" option to make them available.

The "Floppy disk" icon on the desktop points to the wrong mount point. Change its properties to reflect /floppy or change the mount point in fstab to /mnt/floppy.

I usually mount from the command line, i.e.:
mount /dev/cdrom /your/mount/point
Maybe someone else can help with KDE GUI mounting tools.

Good Luck!

Mike