All fly-by-wire is is keeping an inherently unstable airplane (F-16) stable with minute control inputs that constantly adjust the control surfaces to allow smooth flight in an aircraft that would normally be unflyable. It also allows for automatic use of the rudder when necessary, eliminating the need for pilot rudder inputs. This is pretty much what elite already said, however, it is already modeled in the "auto-rudder" option (as they are inherently the same thing).
As for thrust vectoring and VTOL flight, that is something that has to be modeled into each aircraft individually. Many FS9 aircraft already have VTOL capabilities, like the IRIS Harrier and F-35 (see pic below). Thrust vectoring only allows an increase in agility and it allows the aircraft to maintain a certain degree of control in a post-stall flight regime, meaning the aircraft can still maneuver in a stall, or when there is no airflow over the wings, which again, would have to be modelled for each aircraft, unless a much more advanced flight model was used, which actually simulated airflow over the wings (which is very doubtful).
Pic of VTOL flight (WARNING contains PAYWARE), IRIS F-35 in a hover....

