For (5) under Programming and Erasure Procedures, FCU Command Usage, FCU, in the Flash Memory chapter of the User's Manual: Hardware, it states that "In cases where the target range... includes addresses that do not require programming, use FFFFh as the data for programming to those addresses". If FFFFh is used as the data for programming to addresses that do not require programming, does that mean that that area is not programmed?
No. FFFFh is written to the addresses for which FFFFh is used as the data for programming. Thus, the area is programmed (with FFFFh). The only exception is when FFFFh is specified for an entire 128-byte area.