It's a little late, but I suggest you do more research before buying a plasma tv. Mot to put you down or anything, but you lack of knowledge on different ratios of movies says it all. I'm glad you took back the upconverting dvd player. Those things to me are a big waste of $$. Your tv upconverts the signal to its native resolution. The only difference in PQ would be if the dvd player did a better job at upconverting than the tv. Since you seem like e newbie to the A/V scene, you probably would never see the difference. Why do you want an upconverting player anyway? My guess is that the salesman told you you need one, right.
To fix the green push, turn off the color management. That stupid thing should never have been put on the tv's in the first place. If you have a copy of Shrek, watch it while switching color management on/off. It's literally unwatchable with it on.
As for picture settings, you may not know that the default settings of your tv will kill its life span. The picture(contrast) setting is maxed out by default. Turn it down to around 50%. You may want to turn the sharpness way down too to get rid of horrible edge artifacts. Everything else is set to 50% buy default. Keep the brightness around this level and adjust the other settings to your liking.
You have an awsome tv, now just do some reading so you can make the most out of it.