Beginner Surfer Tips

As the title says i've just beginning to surf. I have a few questions that could maybe you could answer. First i wanted to know if it is that much harder to learn on a short board? Im 15 and im 5' 7" and about 110lbs. I know that long boards are more stable and give me more room for my feet but since im lighter would a short board be easier for me to learn on? Second im a pretty decent swimmer in the ocean. Ive been boogie boarding since ive been 8. I live in so cal and was wondering how thick a wetsuit to get? If your not from so cal the water is bout 55 degrees Fahrenheit in the winter and almost 70 in the summer. Third, do i need to take lessons? i know itll make it easier but really dont want to spend the money. Is it possible to teach myself? And lastly, ive always had this fear of deep water in the ocean. Being behind the breaking waves just makes me uncomfortable. Is this something that is just natural and will go away as i surf?