NSA is an agency of the Department of Defense. CIA is an independent organization. FBI is counted among the set of US "Intelligence" organizations, but if there's one thing media and memoirs tell us, it's that organization in different Departments have a history of not playing nice. Case in point, all the finger pointing around organizations not sharing information pre 9/11.
DOD and DOJ in particular I don't think have such a close buddy-buddy relationship.
They have limited access to some intelligence databases and information. That doesn't mean that they can just pop random selectors through PRISM for the lulz though - nor does it mean that the FBI and NSA share everything they have on everybody, or at least they don't for now.
As to the point about selectors, if a selector has an even remotely domestic terrorism related component, and is authorized by the FISA court, the FBI can and does see that information.
DOD and DOJ in particular I don't think have such a close buddy-buddy relationship.