Clevair.shop, sales

I need some help with selling something., have a domain and art work already lined up, need to be able to integrate the app website with stripe or squarespace payment. It’s one item with 2 options individually purchase or bulk purchase. Will need to be able to issue individual special promo codes to lower the price of the item when someone buys it. Ie . code names( 2wave, Azlocal, calilocal, Txlocal, breathright, ) stuff like that. Creat an Acct to logon and track purchase and shipping . Also track how many times per code was used. To track analytics of what marketing is working. Back in of software, need to be able to pull up individual Acct and input messages to customer and tracking information Through USPS .