1. If your blu-ray player decodes the sound internally then you will need a receiver that can accept multichannel PCM through HDMI to be able to hear the new high-def formats since that's what the player would output after decoding. Basically regardless of the format (Dolby or DTS) you would see "PCM" light up on your receiver.
2. If your player doesn't decode the new formats on-board then it will need to bitstream them through HDMI and you then need a receiver that can decode the new formats. In this case the receiver should show "Dolby TrueHD" or "DTS HD" when playing them.
3. Bitstream means that the player just outputs the compressed soundtrack as it is on the disc and lets the receiver handle the decoding. PCM is a digital sound encoding format that is uncompressed (it's the format used on audio cds by the way), and that's usually what a player will output after decoding the new formats internally. In the end it shouldn't matter which one the receiver gets since they both should give you the same data as the new high-def formats are lossless and even in the case of bitstream the sound data ends up decoded as pcm before sound effects (if enabled) are applied by the receiver internally.
Does that make sense?
