On PS3 do u need the other red white and yellow cable i u have a hdmi cable.?

May be...

If you have an HDMI hooked up that is all you need, it reads just from HDMI.

Depends on your setup. HDMI carries both audio and video signals, but if you want to get the sound out of your sound system (and your TV isn't connected to it) - use RCA cable or (if your system supports it) optical out. My TV is plugged into my sound system, so I'm using only HDMI cable.

no, HDMI will carry both audio and video signal. No other cables are needed.

nope