Importing attributes from an external data source to existing AD user objects

I have an Oracle DB with ~1000 users records.  Approximately 300 of those users exist in my local AD.  I want to use FIM to import several data elements (employeeID, manager, and  few custom fields) from the oracle DB user records into the 300 respective AD accounts only, I don't want to import all 1000 users into AD.  Further, some of the data I wish to import will require custom attributes to be added to the AD user object schema.  Can FIM handle all of this on a recurring basis (weekly replication)?