I see that the Passe Navigo Découverte covers airports and zones 1-5. Do we have to choose one zone? or does it cover ALL 5 zones? meaning, pretty much all travel a "typical tourist" would need? (I believe it to be all 5 zones, but I don't want a surprise)
Navigo covers all 5 zones by default, unless you specifically ask for something else that usually only locals traveling purely outside of the central Paris zone would ever ask for.
Navigo (in its 5 zones of coverage) will cover everything a typical tourist would want to see including sites outside of Paris such as Versailles, Disneyland and Fontainebleau.
If the location is within the Ile-de-France region, it's generally covered by Navigo.