Geometry:quadrilaterals and polyhedron

Will any four points in space determine a quadrilateral? What is an example?
Is there any group of four points that don't determine a quadrilateral?


What is the smallest number of faces a polyhedron can have? The greatest? Smallest number of vertices?

In order for four points in space determine a quadrilateral they must be coplanar,
no three of which are collinear.

For information on polyhedron:
http://mathworld.wolfram.com/Polyhedron.html