Where to eBay expenses, etc.?

Hello all.

 

This is the first time I am reporting eBay sales  so I would like your help to make sure that I do this correctly. Last year I sold about 200 items on eBay.  I had to pay quite a bit for these items and I do have records/receipts to show how much I paid.  However, I am unsure where to enter these costs.  Should I do this under the Inventory tab?  If not where?

 

What about those items for which I no longer have receipts?  Should I use "fair market value" as my cost basis?

 

Lastly, where do I indicate the fees that eBay added to my "Gross Amount (Box 1a) (e.g., postage, taxes, etc.)?

 

Thanks in advance to all of you!!!