History and exam. Parkinson's is usually diagnosed based upon it having very characteristic symptoms and exam findings - namely asymmetric (i.e. Usually starts on one side) tremor at rest, slowness of movements (bradykinesia), and stiffness (rigidity). There are some nuclear medicine tests that show the pathology of pd fairly reliably, but they are fairly new and considered experimental by most insurers.
Clinically. There is no proven test. Neither MRI s nor ct scans diagnose parkinson's. The diagnosis is clinical and done by an experienced physician usually there is rigidity, akathisia, shuffling gate, lack of expression of the face, involuntary tremors of the arms, head or trunk, pill rolling tremor. Early Parkinson's is very difficult to diagnose for sure.
Parkinson. Despite a good deal of investigation so far there is no known causes of Parkinson's except for those drug induced. So until the source is found the concept of prevention remains remote.
Surgical? Essentially there are medications and surgery. Surgical treatment would likely consist of deep brain stimulation or dbs but, you should confirm this with a neurologist and a neurosurgeon.