Where are congestive heart failure clinics located?

Various places. Most are within a hospital or a hospital outpatient clinic. They could be in a private office as well.
It depends... Most cardiologists, like myself, treat patients with different types of heart failure both in the office and hospital settings. This is usually satisfactory for most patients. If you need more specialized care, such as consideration for an assist device, or transplant i would consider evaluation at a transplant center.