Yes, a Membership Site can be linked to as many products as you like. Just select the membership site from the content page in any product you want to be connected to the site. Here's how...
You can set the different pages to be viewable by different products. There are a few ways to do this.
Please note that your Membership Site will need at least one page that is published and not hidden, to serve as the home page of your site. Otherwise, your members will not be able to access the site.
Here's how...
One Site for Multiple Classes is an option for when you allow commenting that is only viewable by the class.
Do you have the commenting turned on on your pages but only want it viewable by the class that is commenting and not future or past classes?
To do this you will duplicate the content pages that you allow commenting on to the same site and make those new pages viewable only by the new course or drip them to only the new class.