1) No the locations are not the same. To get to the point (3,0), you would move 3 units to the right of the origin. To get to (0,3), you would move 3 units up from the origin. The origin is the starting point every time to help set a frame of reference.
2) The origin (0,0) is the only point in which you can reverse the coordinates and have the same location
3) This is basically a repeat of problem 2 above. The same answer (0,0) which is the origin applies here.
