You can save descriptions with your new and existing items! When you add or edit an item from your online Dashboard, you'll find the description box towards the bottom, see below:
One thing I'll add is that the description will not appear within the app when adding an item to sale. So if need be, you can also add a note to the item or transaction. Hope that helps!
Next question...my categories are set up as vendor names. If an error is made during checkout, can just the category be changed or do I need to go through a refund and re-enter?
Gotcha, yeah, you could use the note function to add "blue rocker," or one-off descriptions.
Once a transaction is complete it cannot be edited! That's correct that a new sale would need to be made.