UCTD is when you have overlapping connective tissue disease that is not clearly defined. It seems to be a catchall phrase and from what I know it is treated the same as many other AI diseases.
I have MCTD which is lupus, scleroderma and polymyositis. Not a desireable combination. If lupus is the disease with a 1000 faces, MCTD is the one with 10000 faces.
UCTD could include a myositis disease, lupus, RA, or others. Many of the symptoms you list are caused by your disease and are secondary to it. Raynauds is a good example. Kidney and liver involvement are often involved....I have all those and more.
Prednisone is the normal med but usually imuran or methotrexate are also given. The goal is to wean off of pred and let the other med do the job. There are several other common immuno suppressants that are used for some patients.