The most frequent cause of hyperT is an autoimmune condition known as Graves' disease. You should have a TSI antibody test to look for the ABs that cause it. Stress is known to aggravate Graves', but I don't think it directly causes
Another cause is a "hot" nodule, an abnormal growth on the thyroid gland that produces excess hormone.
Excess thyroid hormone can cause all the symptoms you described.
Treatment varies according to the cause of the hyperT. I recommend you get a copy of Thyroid for Dummies
by Dr. Alan Rubin, which will explain everything in easy to understand language.
Not much preparation is needed for an endo appointment. He/she will do a basic physical, heart, lungs, reflexes, etc, and ask about symptoms. Blood will be drawn again, probably. One thing you need to be aware of: If you're found to have Graves', some endos will automatically and immediately push you to have your gland destroyed with radioactive iodine (RAI) in order to control the disease. I urge you not to immediately agree to this without exploring your alternatives. I only mention this because I once read an experience here where someone saw an endo one day, and he scheduled RAI for the very next day. That's unprofessional and never necessary.
After you find out why your gland is working overtime, let us know... especially if you get a Graves' diagnosis. Someone will help you decide upon your options, if you want that.
Sorry you got no response to your first post. HyperT is 8 times less common that hypo (which I am), and so there are fewer hypers here to help at the moment. I try to leave hyper questions to others, since I have no experience with it. But I hope this helped some.