What are the role and responsibilities of "fleet captains"?
A fleet captain basically deals with fleet specific issues. For instance if a new procedure is introduced in the company how is this going to be implemented on the fleet. The most recent example in my company has been the implementation of "RNP" approaches (GPS only approaches) that was introduced across the company but what does it mean for our fleet; where is this displayed on our specific aircrafts what calls should be made depending on the various cues we getting our aircraft etc...this is the kind of answers the fleet captain would have to give to the Chief Pilot in the this example the training department would be heavily involved as well with the respective CFI's(Chief Flight Instructors) again fleet specific. Depending on the company structure the fleet captain might be associated with daily issues or even disciplinary procedures in association with CP, HR etc...
Hope that helps :-)