Technology wise, I am considering PHP, Node.js, Java, RoR but am open to suggestions. As I am the one who will take the decision, I'll go with what the community suggests.
Language doesn't matter that much, your database choice however does - for ecommerce, make sure you use something that is fully ACID compliant.
Amazon is running on Java - as one of the biggest ecommerce companies out there, I'd say that should be considered battle-tested.
To squeeze most out of
This is a too much general question to answer it easy. Take a look at my comment here to similar question. hashnode.com/post/what-do-i-have-to-know-to-build…
It's not really about the language or stack. You will probably end up with a mix. Some parts of in one thing, some parts in another stack.
E-commerce is complicated. It's probably best if you modularize your development in different sub-projects:
There are so many things you need to implement that it can become overwhelming.
That said, you don't really need to do it all at once or write it all yourself. You can start with a simple catalog of Products and Categories and use other services for other things. Like using Stripe for Payments, Customers and Orders. Read a bit more here.