Quote Originally Posted by amarmistry
Got few questions:

1. So lets assume I only have an HDMI Player like Blu Ray and an HDMI TV (no receiver or external speakers at all), I'd connect one HDMI cable from Blu Ray to my TV and I am done. In this case HDMI will carry all audio and video.

This is correct

2. So now lets say if I add an HDMI receiver and surround speaker to the above setup. I'd connect HDMI Blu Ray to the receiver and send video output to my TV via HDMI and 5.1 channel surroud audio to external speakers using individual speaker cables. So, in this case what will happen to the HDMI that is going into TV? Will it also carry audio signal and still play thru the TV speakers?

Yes. Some TV's you will have to turn volume all the way down, others have an option in the set up to turn the TV speakers off. Some brands I'm not familiar with may even have other ways of dealing with it.

3. Now if I replace the TV in above case (2) with a projector (with no built-in speakers), I'd still connect the HDMI from receiver to the projector and 5.1 channel surround audio going to the external speakers using individual speaker cables, what will happen to the audio signal going into projector via HDMI?

Not sure, I assume it just dead ends.

4. To complicate this further, if I had non-HDMI receiver in the above case (3) and if I connect the Blu Ray directly to projector via an HDMI cable for video and 5.1 channel audio from Blu Ray to receiver and and then from receiver on to the external speakers using individual speaker cables, what will happen to the audio signal going into projector via HDMI directly from Blu Ray?

same as above answer.

I am sorry but I am just trying to understand the audio and video signal distributions. are the HDMI devices smart enough to process the audio video signal correcltly? i.e. in case 4 and 5 aboove, is the HDMI in to projector configured (physically or via firm-ware) to not accept/process the audio signal? Will there be any "harm" done to the projector per se?
Rest assured the audio and video signals inside the HDMI are perfectly separated and no harm will come to the projector. There's several strands of cable inside the HDMI, one strand to each pin of the terminal, each pin is responsible for a different job. I suspect unused audio just dead ends.