Upvote:4
It depends on many factors (whether this is your first Schengen visa, your nationality, purpose of visit, international travel in past). If this is your first visa, expect to receive a single entry visa covering just those four days.
Yes, it is possible if the purpose of the visit is the same as on your visa, and your visa is multiple entries.
You can try to provide those itineraries (together with the relevant documentation, tickets, travel insurance etc), and attempt to get a multiple entry visa covering all those. The success of this strategy here in US had mixed results - some people got lucky, some people were not. If your next itinerary is mostly in France, this may also tilt the scales in your favor - but even in this case you might get the visa valid only for the combined days of both itineraries.
Upvote:5
You are confusing the 90 day rule as a default. This is the maximum, the actual duration of your stay is printed on the visa that is issued to you.
So it is quite likely that you may be given a duration validity of exactly 5 days, and a visa validity of 14 days (or something like this) - especially if this is your first time applying.
As there are limited border controls between Schengen states, you are free to roam within the Schengen zone - however, keep in mind your visa must be valid for the entire duration of your stay - in other words, you must leave before the visa expires; and before the duration of stay (whichever is earlier).