#1 is addressed in your phone settings. you can set it so hardware buttons wake up the phone. no app necessary.
*edit... your end call button should work while the screen is off. sometimes it takes a double press.
#4 yes, use the touch dialer located here and at xda.
2&3... yes there are many apps that can help you control volume and closing programs. these are usually mappable to keys via settings.
Try this app for volume. works for me
