User security / permissions

Hi,

I'm sure this is straightforward, but I'm afraid I'm stumped on this one!

I'm building an app that would have one or two "admin" users. These users would be responsible for adding / deleting / editing records in the database. They would have special screens that only they should see, for making changes to the data. No-one else should be able to see these admin screens, or be able to modify any data.

But everyone in the world should be able to view all the data in the system. The public, anonymous user must not be prompted to log in, and they should have access to most of the data viewing screens / navigation in the application, and be able to invoke certain custom actions to bring up pop-up screens, etc). (None of these generally available screens would have any custom actions that allowed data to be modified).

I'm not sure how I should set up the security? Should I make the app private, but share the "safe" screens with the public (anonymous) user? Is this possible?

Or should I make the app public, and have some Deluge script that detects who the user is, and redirects the user if they try to access an admin screen (is that possible)?

Any thoughts much appreciated,
Cheers, Katie