FSOCS must be installed on the front-end pool servers (required). Installation on the Edge role is optional, however it is recommended as well. (
http://technet.microsoft.com/en-us/library/cc676966.aspx)
Running client A/V such as Forefront Client Security is supported as well, however some exclusions will need to be configured to ensure that the client A/V does not interfere with FSOCS. (
http://technet.microsoft.com/en-us/library/cc676981.aspx)
HTH,
ShreyS [MSFT]