Measurements of the electrical resistivities, Hall coefficients RH, thermoelectric powers S, electronic specific heat coefficients gamma have been carried out for the superconducting system LnFe1-yMyAsO1-xFx (Ln=La, Nd; M=Co, Mn; x=0.11). NMR longitudinal relaxation rates 1/T1 have also been measured for LaFe1-yCoyAsO1-xFx. Co atoms doped to LnFe1-yMyAsO1-xFx are nonmagnetic, and their Tc-suppression rates seem to be too small to be explained by the pair breaking effect of the Co impurities for the superconductors having the S+--symmetry, which has been theoretically proposed as the most probable one. Upon the Mn doping, the system becomes nonmetallic at a very small impurity concentration y and the superconductivity disappears. We propose that there are two mechanisms of the Tc-suppression: One is the electron localization and another is the disappearance (or reduction) of the hole-Fermi-surfaces, which have strong magnetic fluctuations essentially important for the determination of the transport behaviors. The latter mechanism have been observed, when the electron number increases with increasing Co-doping level. On the two distinct T dependences of the NMR longitudinal relaxation rate 1/T1 of LaFeAsO1-xFx, 1/T1 proportional to T6 observed by our group in the wide T region from Tc to ~0.4 Tc, and 1/T1 proportional to T2.5-3.0 observed by many groups in the almost entire T region studied below Tc, we discuss what the origin of the difference is and clarify which is the intrinsic behavior. On the basis of these results, arguments on the superconducting symmetry are presented.