  We present a complete analysis of the Fundamental Plane of early-type
galaxies (ETGs) in the nearby universe. The sample, as defined in paper I,
comprises 39,993 ETGs located in environments covering the entire domain in
local density (from field to cluster). We derive the FP of ETGs in the grizYJHK
wavebands with a detailed discussion on fitting procedure, bias due to
selection effects and bias due to correlated errors on r_e and mue as key
factors in obtaining meaningful FP coefficients. Studying the Kormendy relation
we find that its slope varies from g (3.44+-0.04) to K (3.80+-0.02) implying
that smaller size ETGs have a larger ratio of optical/NIR radii than galaxies
with larger re. We also examine the Faber-Jackson relation and find that its
slope is similar for all wavebands, within the uncertainties, with a mean value
of 0.198+-0.007. The variation of the FP coefficients for the magnitude
selected sample from g through K amounts to 11%, negligible, and 10%,
respectively. We find that the tilt of the FP becomes larger for higher Sersic
index and larger axis ratios, independent of the waveband we measured the FP
variables. This suggests that these variations are likely related to structural
and dynamical differences of galaxian properties. We also show that the current
semi-analytical models of galaxy formation reproduce very well the variation of
age and metallicity of the stellar populations present in massive ETGs as a
function of the stellar mass in these systems. In particular, we find that
massive ETGs have coeval stellar pops with age varying only by a few % per
decade in mass, while metallicity increases with stellar mass by 23% per mass
decade.
