If you are taking a class, it is good to practice at home. As for that lean, looking body, it depends on your body type. For me, running just makes my leg muscles bulk, but for others, they are able to get a lean look. Find what works best for you. I have a better shape because of belly dancing. Other forms of cardio were not for me.
When you rotate your hips, just please make sure to tuck in the pelvis. Tucking in the pelvis works the abs. This prevents back injuries.