1. Your upgrade should have restored from the old OS... did you edit or remove any cod folders from the OS upgrade, via John Clark's Mem Optimization thread?
2. Yes, you can save any picture you like for your wallpaper from your device, just select the picture > Menu > Set as Wallpaper. There is not a rotating automatic slideshow app to change it for you automatically.
3. There are no templates, but there is AutoText. (there could be a third party application for this, I don't know of one off hand.)
4. Hope it works for you.