Upgrading to SP2

Hi,

We are planning to upgrade our SharePoint 2010 farm to SP2. We are also using FAST Search Server 2010. My question is, do we need to also upgrade the FAST Server to SP2 if we are upgrading the farm to SP2?

Is there also a documentation for the correct step by step process to upgrade to SP2. Our farm has 3 WFE, 2 App Server, 1 DB server and 1 FAST Search Server.