The screened QED corrections of the first orders in \alpha and 1/Z to the g
factor and the hyperfine splitting of lithiumlike ions are evaluated within ab
initio quantum electrodynamical approach. The complete gauge-invariant set of
the two-electron self-energy diagrams in the presence of the magnetic field and
a dominant part of the two-electron vacuum-polarization diagrams are
calculated. The most accurate values of the g factor of Li-like lead and
uranium are presented. The theoretical prediction for the specific difference
of the hyperfine splittings of H- and Li-like bismuth is improved.Comment: REVTeX, 29 pages, 3 figure