Are there long-term side effects of Radiesse? Or do any negative side effects happen immediately after injection?

I think Radiesse if a fine product and can give excellent results.  It is possible to get bruising and swelling with any injection, so these side effects are not particular to Radiesse.  Any filler can also cause some bumps or lumps, which you do not have at this point so I would not expect you to have any problem with them.  I would feel comfortable with your choice and am glad that you obtained good results. 

Radiesse is one of my preferred fillers to use. It provides a nice lift and is semi-permanent in the sense that it lasts about 18 months. Compared to other fillers, it is associated with more swelling. In addition, because it is made of calcium hydroxylapatite, this product may show up on an X-ray or CT of the face. There are no additional side effects compared to other fillers. 

I don't know what side effects you are referring to. Lumpiness can occur but, frankly, that is more a consequence of poor injection technique than the product itself. I do not recommend placement of Radiesse under the eyelids and Restylane is a better product for patients with extremely friable, fragile skin.  Filler does need to be customized to the patient and I am glad that you have had a good experience!