Quote Originally Posted by Seph

3. What exactly is Dolby Pro Logic II? I understand that it can take standard two-channel audio and "splice" it into 5.1 surround, but why would someone use this codec when playing audio that is already encoded in 5.1 channels? Isn't this redundant? Basically, if a movie is already playing in Dolby Digital 5.1 or DTS, why would I want to enable Pro Logic II?
Yes you are correct about Pro Logic II....read your post again, you answered your own question

"why would anyone use this for something already encoded in 5.1?"...well you don't...like you said Pro Logic II was designed to be used with 2 channel sources, not 5.1 channel sources. It can take a 2 channel analog signal and 'make up' the information to send to the center and surrounds. I use it when watching TV and it actually works quite well for that.

As far as the other two things...well quite honestly things like that are found on low cost units to make the user think he's got something cool. Once you upgrade to an a/v receiver you'll find that such trickery is quite useless.