Liposuction. Good idea? What are the potential long term side effects?

Minimal with skill. Liposuction is one of the safest cosmetic procedures when performed by a skilled, trained cosmetic surgeon. Tumescent liposuction is the key, where the tumescent fluid decreases all the potential risks of liposuction, including a decreased risk of bleeding and infection, plus a marked decrease in dvts and pes since it can be performed awake, without a general anesthetic.
Not for weight loss. Liposuction can be a good way to trim and sculpt areas of unwanted bulging. If you are overweight or obese, it is not a good way to lose weight. There is only a certain amount of fat that can be harvested at a time, due to regulations. Side effects can include pain, infection, abscess, and the standard risks of anesthesia or sedation. Talk to your surgeon.
Good idea for most. Liposuction if properly performed is safe and has no long term side effects. You should maintain a healthy weight to maintain results.
Depends. Liposuction is an ideal treatment for localized areas of fatty deposition beneath the skin with the expectation that after surgery there will be retraction of the overlying skin and improvement of the contour. If the skin cannot be anticipated to retract, surgical excision of the skin and fat would be more appropriate. Long-term problems of liposuction mostly involve irregular contour of the skin.