Is it possible to use HDMI input, to Receiver, Then output to component?

What you describe could be quite viable. The receiver should have a mode which determines which of its inputs get sent to the speakers and projector. You're getting audio from the PS3, which means you already have the right input mode selected on the receiver. Now you just need to get the video to the projector.

If this isn't happening immediately, first check if the projector is on the right input to get video from the receiver.

You will also want to check that there is actually a connection to send video from the receiver to the projector, as it's quite possible your parents use the projector without it (instead being connected directly to the DVD player, digital TV set top box, cable TV box or whatever).

However the Marantz outputs video to the projector, is the same method you should use to connect video to the Marantz, but digital video is passed by component, DVI or HDMI only. For digital Audio, your options are coaxial or Toslink (fiber optic), coax preferred, but Sony only does Toslink. HDMI is digital Audio AND Video. You may have to experiment with hookup a little to find the solution, it depends on how the system is wired, how new is the equipment and what options are available to you

The video connection to the projector is the key usually, the audio option will follow from the input/output on the Marantz. I think the PS3 has a yoke that has component video outputs. this is what you should use.

sorry buddy... you cant down-scale the picture quality.. what i would recommend is running HDMI directly to the projector then a seperate audio to the surround or even running another hdmi from the receiver to the projector for video.

No.

You would need to spend a few hundred $$ to get an HDMI to component converter.