The player states (core only) for the new audio formats. I would imagine this means it does not decode the signal. If it doesn't decode the audio, your receiver can't use it. Again, I am not up on the two new formats.
You want to do your homework, and be sure this player decodes these formats. Otherwise, you are paying for DTS-HD and True-hd that you can't use. Not to mention, paying for 1080pHD to be displayed on a 720p TV.
As far as your receiver not accepting audio throug it's HDMI input, that just doesn't make sense.