Small Company Intranet Applicability?

Hi All,

I am searching for an app to be used as a first step for a small company (<50 users) intranet. We have folks spread out across the states and would like to have a place for them to communicate.

Questions:

1) I assume that you can setup the system so that NEW USERS have to be authorized by an admin before they can read or post, is this true? (not on by default I am presuming since I was able to register and post without this...)

2) The documentation lists the ability to upload files. We would like to have users be able to access this on a limited basis, can this be set up on an "as needed" basis by the admin?

3) Is the performance that much better with the SQL Server version?

4) Once the app is installed, I am assuming that all the admin tasks can be done via a browser.

TIA