The Threat Detection feature comes with version 8.x. You can find it in ASDM under "Configuration" -> "Firewall" -> "Threat Detection"or on the cli (example):threat-detection basic-threatthreat-detection scanning-threat shun except object-group admin...

You can't block AOL. MPF only supports blocking Yahoo and MSN.The example of Cisco:class-map imblock match any // or aclpolicy-map type inspect im impolicy parameters match protocol msn-im yahoo-im drop-connection // or log , resetp...

For blocking instant messaging like msn you don't need an AIP-SSM.You can block such traffic with the modular policy framework of asa os.http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a00808c38a6.shtml

You must configure one more Virtual Context (webvpn context $name$) with other aaa parameters

Yes, you need the CSC Module to anlyse mail-traffic. Have a look at the different Software-Levels of the CSC. Not every Version includes the Spam-Filter (Plus-License required).http://www.cisco.com/en/US/products/ps6120/products_data_sheet0900aecd804...