Changing a moving background to a different one depends a great deal on movement. If complex the task would be difficult and very time consuming in Vegas since it doesn't have the ability to easily mask out bulk areas. Give more details.

As far as change the colors of some isolated objects, that too depends on what you want to change also appears elsewhere. For some idea see my tutorial #12 below.

http://www.wideopenwest.com/%7Ewvg/tutorial-menu.htm