Contorl D is the duplicate function and you can set up the X and Y offset. If I have a 1" square and want a 5 x 5 grid with .5" space, I will set up the X offset to 1.5" and Control D 4 times. The zero out the X and set Y to 1.5" and Control D 4 times.
Radial, use the transform menu. Draw a...