Noob-style question regarding lossless audio

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I have a Sony BDP-S301 connected to a Denon AVR-2105 Receiver.

The receiver is older and doesn't know anything about HDMI. I can plug into it digitally (coax or optical) or via the 5.1 analog inputs.

My questions are thus:

If I throw in a movie and select the PCM-Uncompressed soundtrack, what is being sent to the Denon? I'm pretty sure the uncompressed audio is going over the analog connection, but is it also possible for this to go through the TosLink cable?

How about for TrueHD? I assume I'm getting 5.1 uncompressed on the analog inputs and a standard dolby digital stream over the digital cable. However, on the receiver when playing back a TrueHD soudntrack via the optical input, the display shows Dolby Digital EX.

If it's really putting out an EX core, am I losing my surround back channel when I'm going analog?

Finally - how does it handle DTS-HDMA? I know the player doesn't fully decode it - it only pulls out the core. Which connection should be giving me the best audio here? I'm actually hard-pressed to hear much difference between the digital and the analog here. If anything, my ears tell me the DA converter in the Denon is probably doing a better job than the one in the Sony.

I guess what I'm really trying to decide is how much longer I can get away with using this receiver. A lot of the newer players don't have analog outputs, so if I get a new one I want to know how much the loss of the analog outputs is going to hurt me.

Thanks for any advice!

ryan