How do Pro Sites and New Blog Templates interact?

My Pro Sites setup has 3 levels: Free, Standard, and Pro. I'm using the Premium Themes and Premium Plugins options in Pro Sites. One of the premium plugins, for example, is the AddThis Social Sharing plugin.

Can I just make *one* template that includes AddThis, and then let ProSites filter it out for non-Pro members? Or do I have to make multiple templates, one for each of my 3 levels?

Also, do I have to make a separate template for each of the themes I will be offering my users?

Thanks in advance,