Questions on different sound modes for new codecs,DOLBYTRUE,DTS MASTER

[ozzman]

This might be just a simple question for someone but for me it drives me crazy not knowing.

Now when iam watching a blu movie in 5.1 and its set to DOLBYTRUEHD i have a couple sound modes and this is what they are

-DDHD-PLllXMV
-DDHD+DDEX

There's a couple more for music.My question is when i select these modes iam i still useing DOLBYTRUE 5.1,Just modifying the sound for my back surround speakers?

Next question When useing DTSHD MASTER,If the movie is in 5.1 can i make it to 7.1 Making the back surround in use and still decode DTS master(i know its not true 7.1)Or is the only way to get all my speakers to work is just to keep purchasing 7.1 DTSHD MASTER movies ?(example the new RAMBO)

Is there a reciever that can do that ?

I have a Marantz 7002
I have searched the net and can't find any answers,Iam just looking for one Brave soul that thinks he can help me .Believe me iam kinda embarrassed asking these questions but when you don't know,you don't know?

If it matters iam bitstreeming into my reciever with a Samsung 1400


Any comments or suggestions about this subject can help immensely THANK YOU