The coordinate of point A is (2,0), point P is on the image of function y=-x+3, the origin is O, let the area of a triangle be S, and the coordinate of point P is (x, y).

1. Finding the area is the range of the functional relationship between S and X.

2. If the distance from point P to Y axis is 2, find the area of triangle OPA.

3. If the area of triangle OPA is 4, find the coordinates of point P..