To mount a cd (need to create /media/cdrom if it doesn't exist):
mount -t iso9660 -o ro /dev/cdrom /media/cdrom
to mount a floppy (a dos floopy)
mount -t fat /dev/floppy /media/floppy
The above can be done more easily if you have entries for them in your fstab.
You need to unmount them before you remove them:
To mount the usb is more complicated. You need to know what the device of the USB is.