"Describe your business" would be online selling. The "name for business and business address" are determined by you. If the business address is your home address, then that is what you use. The business name is the hard part. You should have already determined that, but you can correct that now. Your business name is not eBay. They are a separate entity. You need to find the business code under retail sales for online sales.
Personal property that is later sold is sold at fair market value. That property only becomes inventory when you determine you wish to sell it. You should keep a running tally of the items you sell with the item name, date placed in inventory, date sold, fair market value, and selling price. You will need to determine the fair market value. The normal fair market value unless it is an antique or art is garage sales value.
I hope this answers your questions.
