a cylinder
triangular prism
A cylinder, depending if you think the curved part that goes around counts..
sphere
Cylinder
They are straight lines where two plane faces of the shape meet. The definition is sometimes extended to curved lines where curved (3d) faces meet such as at the base of a cone.
A 3D shape that has 6 edges is called a hexagonal prism.
a circle
square based triangle
cone
A cone would fit the given description
corners of a 3d shape