We are working on the updated installation guide, but you can look at our latest installation guide on Ubuntu - https://grandnode.com/how-to-install-grandnode-on-linux-ubuntu-1604
Yeah, it's some kind of bug. I reported it on our GitHub, here and we will fix it soon. Thanks for reporting.
I noticed very sad thing. You asked for support many times, but generally you don't respect us, as an open source developers. You broke the license terms, when you deleted copyright information from the footer. We will be able to help you after fulfilling the license conditions.
So it's something related with nginx configuration and redirects. Without knowledge about configuration I won't be able to help you.
Basically, plugins from nopCommerce won't work in GrandNode. But, if you are familiar with programming and have source code of plugin, you will be able to migrate it from nopCommerce to GrandNode.
In the case of let's encrypt issues, did you change the UseForwardedHeaders setting in your appsettings.json file?
It's automated. If you create product as a vendor (vendor has to be assigned to specified store), GrandNode will automatically limit this product to particular store. If you assign vendor to existing products, you need to edit them as a vendor (just click save on them) it will update info about store limitation.
Which price was lower? Always the lowest price appears on the product page. It's behaviour of GrandNode.
According to our docs, display order of products on category and manufacturers pages is configurable on product page - section Additional info.
Can you tell me do you have problems with date format or with setting correct time zone?