  When clusters of galaxies are viewed in projection, one cannot avoid picking
up foreground/background interlopers (FBIs), that lie within the virial cone
(VC), but outside the virial sphere. Structural & kinematic deprojection
equations are not known for an expanding Universe, where the Hubble flow (HF)
stretches the line-of-sight (LOS) distribution of velocities. We analyze 93
mock relaxed clusters, built from a cosmological simulation. The stacked mock
cluster is well fit by an m=5 Einasto DM density profile (but only out to 1.5
virial radii [r_v]), with velocity anisotropy (VA) close to the Mamon-Lokas
model with VA radius equal to that of density slope -2. The surface density of
FBIs is nearly flat out to r_v, while their LOS velocity distribution shows a
dominant gaussian cluster-outskirts component and a flat field component. This
distribution of FBIs in projected phase space is nearly universal in mass. A
local k=2.7 sigma velocity cut returns the LOS velocity dispersion profile
(LOSVDP) expected from the NFW density and VA profiles measured in 3D. The HF
causes a shallower outer LOSVDP that cannot be well matched by the Einasto
model for any k. After this velocity cut, FBIs still account for 23% of DM
particles within the VC (close to the observed fraction of cluster galaxies
lying off the Red Sequence). The best-fit projected NFW/Einasto models
underestimate the 3D concentration by 6+/-6% (16+/-7%) after (before) the
velocity cut, unless a constant background is included in the fit. Assuming the
correct mass profile, the VA profile is well recovered from the measured
LOSVDP, with a slight bias towards more radial orbits in the outer regions.
These small biases are overshadowed by large cluster-cluster variations caused
by cosmic variance. An appendix provides an analytical approximation to the
surface density, projected mass and tangential shear profiles of the Einasto
model.
