Well, it really depends on requirements. As such the computer regulates the leading edge slats too. The roll and yaw inputs also go into the computer that coordinates it with the servos in the tail. So its more of a hybrid than separate systems.
Yes it's a hybrid system but still a full FBW will surely save weight and space.
Not possible. Chinese said it would take 2 years for them to build full fbw for JF-17
Actually, in a recent interview they said it's available as an option, at additional cost of course.