(Check the glossary for those terms. SVOboy has done a good job linking the terms to threads that discuss them.)
All 3 of those are different acronyms for coasting the car with the engine off (getting infinite MPG). It's one of the most productive techniques for boosting your city FE. People who do this "agressively" will typically see their city mpg figures rise above what they can achieve on the highway. (EDIT: and people who live in mountainous terrain can do it at highway speeds too.)
The first 2 things netted me a 5.7% increase in highway MPG. I didn't test the wheel covers.
Also, just about everyone here will highly recommend getting fuel economy instrumentation for immediate feedback. Useful for honing driving techniques and testing changes to the car. Check the glossary for SuperMID.