Not sure what you mean by "objects are rotating". With a lens as wide as that, you may be seeing parallax effects with objects close to the lens.
The 15mm virtually guarantees that you'll have the sun in shot unless it's directly overhead. If you use a constant exposure, the area near the sun will be overexposed. What you DON'T want to do is use auto exposure to correct this. The sky tones won't match shot to shot.
Unless you're after a total environment panorama, I suggest a longer lens, especially if you're just starting panos. The longer the lens, the easier it is to create panos. Your fisheye will tax your stitching program to the max.
I shoot most of my panos hand-held with good success, but my lens is only about 35mm at full wide.