Re: #2:
AJAX is typically used to avoid changes in page scroll. If the AJAX itself causes the page to scroll to the top, this benefit is lost.
This is a good UX feature that you mentioned.
So I think it's important to get away from status messages and implement this popup functionality.
Showing the status messages is necessary. While working in 7.x version of this module, people complained that this module does not shows feedback messages, or error messages. So, I do not want to lose this feature in 8.x.
If you still do not want the status messages, you can either fork this module https://github.com/subhojit777/dc_ajax_add_cart, or you can create a new issue and upload a patch there and use it with https://github.com/cweagans/composer-patches.
Re #3:
Thank you for taking the lead :) Some feedback:
- Could you do this in a separate module. Because people may/may-not want the popup by default. Commerce Kickstart has the ability to stop the popup, and I want to retain that feature.