I have asked the lead developer of PowerPress to look at your question and either he will respond here or I'll come back with his response.
I think the challenge you'll face with things like shortcodes being used on Pages on your site is that, the caching plugin is going to cache all of the content on the Page. I don't know if you can get granular enough with the caching controls to tell it to exclude things shortcodes, but all plugins are different, and maybe the one you're using allows for this.