Self employed

I really hope somebody with knowledge answers these questions.  
I was also wondering about items bought last year to list on eBay, but not actually sold until this year.  

I was also wondering if I had to itemize everything I sell on eBay also.  I buy  quantities of Laptops and computers to fix up and resell on eBay.  Some of the Laptops & computers take more investment to fix up than others before I can resell them.