  We summarize recent results obtained in [1] on the running m_{c,b}(m_{c,b})
in the MS scheme and f_{D_(s), B_(s)} using QCD spectral sum rules (QSSR) known
to N2LO PT series, including all dimension-six NP condensate contributions in
the full QCD theory, an estimate of the N3LO terms based on the geomteric
growth of the PT series and using the most recent values of the QCD input
parameters given in Table [1]. The study of the effects of the subtraction
scale \mu on "different QSSR data" and the use (for the first time) of the
Renormalization Group Invariant (RGI) scale independent quark masses in the
analysis are emphasized. The estimates [rigourous model-independent upper
bounds] reported in Table 2: f_D/f_\pi=1.56(5)[< 1.68(1)], f_B/f_\pi=1.58(5)[<
1.80(3)] and f_{D_s}/f_K= 1.58(4) [< 1.63(1)], f_{B_s}/f_K=1.50(3)[<
1.61(3.5)], improve previous QSSR estimates. The remarkable agreements with
some of the experimental data on f_{D,D_s} and with lattice simulations within
dynamical quarks confirm both the success of the QSSR semi-approximate approach
based on the OPE in terms of the quark and gluon condensates and of the Minimal
Duality Ansatz (MDA) for parametrizing the hadronic spectral function which we
have tested from the complete data of the J/\psi and \Upsilon systems. The
running quark masses m_c({m_c})=1286(66) MeV and m_b({m_b})= 4236(69) MeV from
M_{D,B} are in good agreement though less accurate than the ones from recent
J/\psi and \Upsilon sum rules.
