Hi @Islander welcome to Discourse meta, I’ll try to answer your questions
It’s not easy per se but it is a very straightforward process given that You’re comfortable with SSH, Databases and Docker.
Discourse has Supported for Nested categories one level deep. Topics can be created in the parent or sub category depending upon the permissions of the category.
There is a 3rd Party plugin known as Babble, this can be helpful for You.
Not natively supported in Discourse but You are free to make a plugin to do that.