  Metal-poor stars are key to our understanding of the early stages of chemical
evolution in the Universe. New multi-filter surveys, such as the Southern
Photometric Local Universe Survey (S-PLUS), are greatly advancing our ability
to select low-metallicity stars. In this work, we analyse the chemodynamical
properties and ages of 522 metal-poor candidates selected from the S-PLUS data
release 3. About 92% of these stars were confirmed to be metal-poor ([Fe/H]
$\leq -1$) based on previous medium-resolution spectroscopy. We calculated the
dynamical properties of a subsample containing 241 stars, using the astrometry
from Gaia Data Release 3. Stellar ages are estimated by a Bayesian isochronal
method formalized in this work. We analyse the metallicity distribution of
these metal-poor candidates separated into different subgroups of total
velocity, dynamical properties, and ages. Our results are used to propose
further restrictions to optimize the selection of metal-poor candidates in
S-PLUS. The proposed astrometric selection ($\mathrm{parallax}>0.85$ mas) is
the one that returns the highest fraction of extremely metal-poor stars (16.3%
have [Fe/H] $\leq -3$); the combined selection provides the highest fraction of
very metal-poor stars (91.0% have [Fe/H] $\leq -2$), whereas the dynamical
selection (eccentricity > 0.35 and diskness < 0.75) is better for targetting
metal-poor (99.5% have [Fe/H] $\leq -1$). Using only S-PLUS photometric
selections, it is possible to achieve selection fractions of 15.6%, 88.5% and
98.3% for metallicities below $-$3, $-$2 and $-$1, respectively. We also show
that it is possible to use S-PLUS to target metal-poor stars in halo
substructures such as Gaia-Sausage/Enceladus, Sequoia, Thamnos and the Helmi
stream.
