New Product Listing different between get categories and search categories and some other issue

I am tired to find what json say for listing

{ "sellerSKU": "asdas", "categoryId": 307, "attrNameToValueMap": { "Brand": "LG", "EAN": "10000001", "Warranty": "Red", "Liquid": "Red", "Hazardous": "Red", "Selling_Price": "7000001", "Serialized": "Red", "Inventory": "10", "Offer": "10", "sellerImage2": "qc/4F4QU2W0BO.jpg", "new": "2", "sellerImage1": "qc/5F4QU2W0BO.jpg" } }

(what do you means of EAN,Warranty and all)
and also please tell me to when i use get categories then what do you mean of search categories and what is a get attribute for categories i am confused in this please tell me a solution. and at last can i upload multiple image?