1. Are the inside angles of all hexagons equal to 120o?

Only if it is a regular hexagon. This is a hexagon with all sides of equal length.

2. Is it possible for a polygon to have an interior angle greater than 180o?

 

Yes. This type of polygon is called a

concave polygon.

 

3. How are the outside angles of a regular polygon, such as an octagon, calculated?

The outside (exterior) angles of any polygon always add up to 360o. For a regular octagon, each of the eight exterior angles is 360o divided by 8 = 45o