Rule Number 1 (for Q2): be truthful, give a realistic itinerary.
The enter and exit days counts as full days.
Q4: You may not enter before the first day stated on the visa.
Note: Some visas (often first time visas) are issued for a date range. More often a amount of days (duration). If nothing is given then 90 days within a 180 period.
So if the visa is ...