It is not just bitcoins, but all crypto from my understanding that you have to worry about.  From what I have read on the subject I think that it is best to consult a tax professional just to be sure.  There are also local regulations to contend with in some areas, and it would be really easy to make a mistake.

You need to report any time a bitcoin is exchanged, not just when it makes a profit.  Kind of like stocks.  So if you buy something with bitcoins you need to translate to the cost of dollars, and compare that to the price when you bought bitcoins.  AFAIK the irs wants us to use FIFO for bitcoin accounting.  This makes tracking purchases and sales needlessly complicated, and I would seriously consider getting some software to track the stuff for your business.  At least this is my understanding, but the irs has been pretty vague on the issue leading me to believe that there will be plenty of court cases to come.

Best of luck!