SharePoint 2010: Search Windows PowerShell cmdlets
Estimate performance and capacity requirements for SharePoint Server 2010 Search
http://technet.microsoft.com/en-us/library/gg750251(v=office.14).aspx
Plan for crawling and federation (SharePoint Server 2010)
http://technet.microsoft.com/en-us/library/cc262926(v=office.14).aspx