I am looking to develop a commerce system in DNN. For my system I will need to design multiple modules to handle all business. These modules need to interact with each other.  For example a navigation module that is located in the left pane will need to interact with a content module in the content pane.

1) please direct me to an example of intermodule communication.

2) Is there something more coarse grained than a module? I don't want to have to lay out all the modules on a page that need to work together more than once. Is there a way That I can just build pages that work to gether and then if I install that module in a portal. The page can be installed? I plan on having many portals per customer and whoever wants my commerce service can have it installed all together without having to lay out modules. Additionally, i dont want to allow my portal administrators the ability to rearrange my modules, as if they remove a necessary module from a page, it will cease to work correctly.