Yes, this extension works for staging and the live site, as well.  

You have 2 way to add bulk order: Enter Multiple SKUs or Use the quick CSV file

Yes, you can. You can enter as many SKUs as you want to search for all of products with only one single click

There are some ways to change the number of products. You can either use the +/- buttons or directly type the exact number in.

You can use instant search by product names or SKUs, add multiple SKUs or upload a CSV file.

Yes. this extension supports all types of languages so you can easily translate it into your wished languages.

Yes, it can work with all types of products well; simple, configurable, downloadable, and virtual products.

Not using debugging tools like Tag Assistant or Data Layer Inspector. Also, poor testing; Placing dataLayer = after the Google Tag Manager container snippet; Using too many auto-event listeners; Not using a proper naming convention; Tracking form submissions with click triggers.  

Google Tag Manager Community on Facebook; Google Tag Manager Community on Google+; Google Tag Manager Forums; Stack Overflow  

First, you need to have e-commerce data in the Data layer. Then you pass it with Google Analytics Tags to GA servers.