Schema and Feature

The index schema and its features (FAST Search Server 2010 for SharePoint)
There are several reasons to for excluding the content of crawled properties to improve both relevance and recall. Some crawled properties might be searchable through a managed property mapping, and do not have to be searchable through the default full-text index also.
http://msdn.microsoft.com/en-us/subscriptions/gg982954.aspx


FAST Search Query Integration Overview
Using the Query Web Service
Using the Query Object Model
Restricting Search Results Using Search Scopes
http://msdn.microsoft.com/en-us/library/ff394628.aspx

FQL Language Syntax
http://msdn.microsoft.com/en-us/library/ff394462.aspx#fqloperator_filter

Tuning Dynamic Rank
http://technet.microsoft.com/en-us/library/ff453912.aspx