What is the easiest way to get rid of sun spots post production?
The best way to prevent sun spots is to make some changes while shooting: use a lens hood, and don't have the sun itself in the photo. Position the sun behind the subjects, or a tree, or a building...you get the idea :) You can also use your hand as a make-shift lens hood!
Post production...I would say the clone tool in photoshop. The content-aware healing brush if you have CS5.
You mean the little spot about 1 o'clock relative to the sun's position? Since it's in the sky (uniform background color), it can be vary easily cloned out in Lightroom. Actually any photo editing software you use should be sufficient.