  We report the phase-connected timing ephemeris, polarization pulse profiles,
Faraday rotation measurements, and Rotating-Vector-Model (RVM) fitting results
of twelve millisecond pulsars (MSPs) discovered with the Five-hundred-meter
Aperture Spherical radio Telescope (FAST) in the Commensal radio Astronomy FAST
survey (CRAFTS). The timing campaigns were carried out with FAST and Arecibo
over three years. Eleven of the twelve pulsars are in neutron star - white
dwarf binary systems, with orbital periods between 2.4 and 100 d. Ten of them
have spin periods, companion masses, and orbital eccentricities that are
consistent with the theoretical expectations for MSP - Helium white dwarf (He
WD) systems. The last binary pulsar (PSR J1912$-$0952) has a significantly
smaller spin frequency and a smaller companion mass, the latter could be caused
by a low orbital inclination for the system. Its orbital period of 29 days is
well within the range of orbital periods where some MSP - He WD systems have
shown anomalous eccentricities, however, the eccentricity of PSR J1912$-$0952
is typical of what one finds for the remaining MSP - He WD systems.
