CDTVJoystickAd.lha on aminet provides the instructions for adding a mouse&joystick port, de.aminet.net
Another option is to buy a CD1200 trackball from somewhere, this also provides mouse/joystick ports (and also functions as a loooong extension of these ports, nice when playing games on a big TV).
The Jumper is also described in some files on aminet, but anyways:
JP15, a three-pin jumper, is close to the chip labelled CSG 6525A. A jumper cap currently connects two of the pins.
If you move the jumper cap to the other end, the CD-ROM drive and the bootup anims will be disabled, freeing some ram. You will now get the Kickstart 1.3 'insert floppy' screen on powerup instead, and the CDTV will behave like an A500 with ECS and 1 full MB of Chip Ram.
