I have a "small" hiatal hernia, and lately have had pain and swelling in the xiphoid process and around to my back. Could these be related?

Doubtful. The esophageal hiatus (the hole in the diaphragm through which the esophagus passes) can stretch out to allow some or all of the stomach to go into the chest is located just in front of the spine. It would not cause swelling near the xiphoid process. Maybe excess gas in the stomach or colon could cause that. It doesn't sound specific to any one diagnosis. Hope this helps!
Probably not. Hiatal hernia (especially a small one) would be expected to cause symptoms of reflux which can be painful, but generally is not associated with swelling around the xyphoid.