Show Hunter horse classes?

I'm looking to start doing show hunter with my recently broken 5yr old gelding, I have never done this before and I would like a bit of advice on what both he and I should wear. I tend to have as few aids as possible when riding so I never wear spurs, or have martingales, strong bits or double reins on any of my ponies or horses if I can help it. Are double reins and spurs mandatory for competing in show hunter classes? Also I already own a black riding jacket, would this be o.k or does it have to be tweed? What is acceptable for the rider to wear? Sorry for all the questions but I really am not entirely sure what is required.