Wael,

Better you research this your self and at least that will help you also to build your knowlege on ASA. I have answered few of the questions below. the rest you can just google.

1- How to activate Netflow: Only ASA 5580 v8.1 support Netflow.

see http://www.cisco-tips.com/cisco-asa-netflow-support-%E2%80%93-netflow-security-event-logging-nsel/

3- How to monitor specific users and or computers or IP activities traffic & to know the top users causing more traffic: One way is by using ASA Capture Feature. see http://www.cisco.com/en/US/products/ps6120/products_tech_note09186a00807c35e7.shtml

6- How to use web filtering services or integrate the device to use an external web filtering software

ASA can do web filering - see http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a0080940c5a.shtml

Also can be integrated with Web filtering software: Also see http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_configuration_example09186a008088517b.shtml

8- License for the IPS Sensor.

See http://www.cisco.com/en/US/prod/collateral/vpndevc/ps5729/ps5713/ps4077/guide_c07-464689_ps6120_Products_White_Paper.html

9- How to enable or disable specific protocol using CLI

see this http://www.cisco.com/en/US/products/hw/vpndevc/ps2030/products_tech_note09186a008085283d.shtml