Customer Account Login + payment system

Weebly Site Builder: I am building an online Amazon store via their API Affiliates program. I already have the API integrated into my site, but need the functionality noted below. Although it is an Amazon store, i would like customers to login to my site and make installment payments on my site; so not using Amazons login or payment system; however, i will be using Amazons "cart" functions and once they have made all their installment payments through my site they will pay through Amazons basket via some sort of online gift card or Amazon gift card. Customer Accounts - The ability for users to "sign up" to join my site - ie. username (email address) and password credentials - Entering their name, address, phone #, email into a database i can manage and monitor - When logging into my site their Amazon basket will appear with whatever products they have left in it; this should be inherent in the API integration, but not sure how it works when customers login to my site. Payment System - The ability for customers to make installment payments to their account via paypal, [login to view URL] and/or MC/Visa etc. - The ability to manage, monitor and track payments from customers in a database/excel doc. This is all currently done through Weebly Site Builder as that is where i started the site; but perhaps it is not powerful enough to handle it and would need consultation on this as well. Thank you for bidding!