  We present a detailed analysis of the kinetic and mass terms associated with
the Landau gauge gluon propagator in the presence of dynamical quarks, and a
comprehensive dynamical study of certain special kinematic limits of the
three-gluon vertex. Our approach capitalizes on results from recent lattice
simulations with (2+1) domain wall fermions, a novel nonlinear treatment of the
gluon mass equation, and the nonperturbative reconstruction of the longitudinal
three-gluon vertex from its fundamental Slavnov-Taylor identities. Particular
emphasis is placed on the persistence of the suppression displayed by certain
combinations of the vertex form factors at intermediate and low momenta,
already known from numerous pure Yang-Mills studies. One of our central
findings is that the inclusion of dynamical quarks moderates the intensity of
this phenomenon only mildly, leaving the asymptotic low-momentum behavior
unaltered, but displaces the characteristic "zero crossing" deeper into the
infrared region. In addition, the effect of the three-gluon vertex is explored
at the level of the renormalization-group invariant combination corresponding
to the effective gauge coupling, whose size is considerably reduced with
respect to its counterpart obtained from the ghost-gluon vertex. The main
upshot of the above considerations is the further confirmation of the tightly
interwoven dynamics between the two- and three-point sectors of QCD.
