Observation and study of the baryonic B-meson decays B to D(*) p pbar (pi) (pi)

24 pages, 14 postscript figures, submitted to Phys. Rev. DWe present results for B-meson decay modes involving a charm meson, protons, and pions using 455 x 10^6 BBbar pairs recorded by the BaBar detector at the SLAC PEP-II asymmetric-energy e+ e- collider. The branching fractions are measured for the following ten decays: B0bar to D0 p pbar, B0bar to D*0 p pbar, B0bar to D+ p pbar pi-, B0bar to D*+ p pbar pi-, B- to D0 p pbar pi-, B- to D*0 p pbar pi-, B0bar to D0 p pbar pi- pi+, B0bar to D*0 p pbar pi- pi+, B- to D+ p pbar pi- pi-, and B- to D*+ p pbar pi- pi-, The four B- and the two five-body B0bar modes are observed for the first time. The four-body modes are enhanced compared to the three- and the five-body modes. In the three-body modes, the M(p pbar) and M(D(*)0 p) invariant mass distributions show enhancements near threshold values. In the four-body mode B0bar to D+ p pbar pi-, the M(p pi-) distribution shows a narrow structure of unknown origin near 1.5 GeV/c^2. The distributions for the five-body modes, in contrast to the others, are similar to the expectations from uniform phase-space predictions