The shots are likely to be intramuscular, which is a large needle. It nearly put me off doing self-injection, but it's honestly not bad. The nurse had me watch as he did the first shot for me in the side of my thigh, and gave me a packet with detailed instructions. If you're feeling uncertain, ask if you can have the nurse or doctor watch you as you inject the first time to make sure you're doing it correctly.
I can only speak about my own changes, but mentally it smoothed out my mood swings completely and also cooled my temper down significantly. My aggression cooled way down and I have a much easier time focusing on any given situation. Also, now that my emotions are in control I'm also in greater touch with them, and I'm finding it's easier for me to let go of decades-long repression; that is to say, I can actually really feel things now, whereas before I stifled everything.