A space can be linked to as many products as you like. Just select the space from the content page in any product you want connected to the space.
You can set the different pages to be viewable by different products. There are a few ways to do this.
Here's how...
One Space for Multiple Classes 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 space and make those new pages viewable only by the new course or auto-publish them to only the new class.