First you need to know what you want to do before anyone can tell you how to best achieve that.
You said most likely to store documents. Do you want to store the documents as binary large objects in a database or shall there be a database system employed that will help you organizing the actual documents?
The perfect howtos are aimed at setting up a typical webserver featuring apache, php, mysql, email... I don't think that is exactely what you need.
Antivirus programs are genereally not needed in linux environments - except to filter out viruses that could harm Windows computers. So if you run an email server or file server to which Windows clients connect to, you can add another level of security by running anti-virus scans on those files.