Hello, my forum is already on WPforo but I've got an idea and am wondering if it'll work;

Using multi-site install of Wordpress

Create an app.website.com subdomain, use wordpress publishing plugins to make an app

On one of the pages, have WPforo so that app users can access the community

Questions:

I simply use the shortcode to load the forum on the page I make for the forum?

Will personal messaging etc work across all installations?

Will I need 2 copies of each plugin for the main site and the app site?

Can I change the front end appearance for the app.website.com wpforo without affecting the other install? 

Anything else I need to consider?