Do ALL Articulate 360 courses published to web for Wordpress, require "additional sites, plug ins" or just Rise 360?

You shouldn't have to rebuild Rise into SL, the publish output and process to upload is exactly the same. 

Your admin should be able to take the unzipped "published for web" folder and upload it to a folder. 

If you don't want to publish and move folders and just give access to the Rise content, you can publish to Review and disable the comments. Here's an example of what it would look like. Then just use that link.

5-Day Challenge to Improve Your Mental Health [demo] | Review 360 (articulate.com)

Look at it where you're not logged into Articulate 360 so you can see what it looks like for a non Articulate user.