Decay Rate of a Light Source usually requires increased Intensity value.
Decay Rate is typically Linear.
Notice the Cone Angle setting for Spot
Lights, which of course, Point Lights do NOT have.
Use Depth Map Shadow has been covered earlier, but it never hurts to
review, review, review with Maya.
Tutorials on Lighting - Michael O'Rourke
Introduction to Lights
& Rendering covers Point Lights, Rendering, Attribute Editor for
lights, IPR rendering.
Lights tutorial covers Spot Lights, using the t (T in QWERTY) shortcut
to get to a toolbox tool we have never used before user to set the Aim
Point of a Spot Light, Panels > Look Through Selected, Interactive
Adjustment of Parameters, Cone Angle, Ambient Lights, Directional Lights.