  The inhibition of small-scale convection in the Sun dominates the long-term
radial velocity (RV) variability: it therefore has a critical effect on light
exoplanet detectability using RV techniques. We here extend our previous
analysis of stellar convective blueshift and its dependence on magnetic
activity to a larger sample of stars in order to extend the Teff range, to
study the impact of other stellar properties, and finally to improve the
comparison between observed RV jitter and expected RV variations. We estimate a
differential velocity shift for Fe and Ti lines of different depths and derive
an absolute convective blueshift using the Sun as a reference for a sample of
360 F7-K4 stars with different properties (age, Teff, metallicity). We confirm
the strong variation in convective blueshift with Teff and its dependence on
(as shown in the line list in Paper I) activity level. Although we do not
observe a significant effect of age or cyclic activity, stars with a higher
metallicity tend to have a lower convective blueshift, with a larger effect
than expected from numerical simulations. Finally, we estimate that for 71% of
the stars in our sample the RV and LogR'HK variations are compatible with the
effect of activity on convection, as observed in the solar case, while for the
other stars, other sources (such as binarity or companions) must be invoked to
explain the large RV variations. We also confirm a relationship between LogR'HK
and metallicity, which may affect discussions of the possible relationship
between metallicity and exoplanets, as RV surveys are biased toward low LogR'HK
and possibly toward high-metallicity stars. We conclude that activity and
metallicity strongly affect the small-scale convection levels in stars in the
F7-K4 range, with a lower amplitude for the lower mass stars and a larger
amplitude for low-metallicity stars.
