Single app? product generator? sharing models?

Hi guys.

Thinking about application layout here - will appreciate your input if
any of you have been in a similar situation!

Application I am building looks like this:
Info Magazine Portal.
Support Portal for Clients
Portal for Service Providers.

Forums, Chats, Articles, Comments etc. for Interactions.
Role based authentication.

Started building like this:

same for views etc.

But I feel like I am losing a level here…
http://app/infoportal/index - shows me my portal index page.
http://app/infoportal/index - shows me my magazine index page.

But - authentication gets a little tricky… as far as i can tell this
is normally done at class level with the filter_before goodies. So I
cannot really have authentication for separate pages - as they are done
using methods…

Cannot do separate apps, they share too much info. I have a user table,
with roles to define access - all my apps needs access to the models.

As per subject - I have looked at product generator and sharing models.

As I stand now I want to do shared models with separate apps. I might
want to use product generator later to add yet another level, to do
custom infoportals for service providers.

I have installed the shared_models but I dont know exactly hot to use

Any thoughts/suggestions will be highly appreciated…