Racecar driver- hobby vs business?

What is the difference at how much of expenses that I can deduct for being a race car driver and racing?  I am racing to make money and I do receive a 1099 from the track that I race at.  So It seems to me it is more like a business.  However, if I classify it as a business and I do not turn a profit in the upcoming years and the IRS makes me change classification back to a hobby- will I have to pay anything back for the years that I classified it as a Business?  Does it change how much you can write off whether racing is classified as a business vs. a hobby?  2017 was my first year racing.