Yamaha RX-V4600 rear speaker volume;dvd vs VCR

Howdy. I recently purchased a Yammi RX-V4600 for the HT setup. I am kind of new at this so please bear with me. I have gone through the auto setup, used the manual setup and basically read the owners manual like a bible (front to rear & rear to front for days) Can anyone enlighten me on a couple of things please.
1) When I play a VCR tape with Dolby souround encritped audio the system works & sounds awsome. "Goldeneye" movie is the best. Cars, bullets, everything seem to come from in front go behind me etc. When I watch movies using the DVD or the satelite, the rear channel speakers are all but not there. Most everything seems to come from the front three speakers. If I put my ear to the rear speakers, I can hear very small audible sound, but it is very minimal and is almost like a small echo. What's the deal? The only way I can get any volume (to the rears) while watching DVD or satelite is setting the system to 7 channel stereo. But then it isn't in surround, is it....?
2) Also I have listend to movies in avery type of surround setting the unit has. Some are pretty good, some are deplorable and reek of echo & bad delay.
Dolby 5.1, DTS, PLX, PLXII, etc.? When I play a DVD, which one of the plethora of multi chennle settings should I set the unit to, or does the unit pick the right one on "auto"?
These settings are driving me crazy...
Equipment: Sony DVP-NSN900V DVD/SCD palyer, Yammaha RX-V4600, 5 speakers (no sub yet) front large & receiver set to large & EQ set to "check;front" for bigger front mains.
Thanks for any input.
"The old grey matter just ain't what is used to be"
-John