  We present results from luminosity, energy and polarization studies at a
future Linear Collider. We compare e+e- and e-e- modes of operation and
consider both NLC and TESLA beam parameter specifications at a center-of-mass
energy of 500 GeV. Realistic colliding beam distributions are used, which
include dynamic effects of the beam transport from the Damping Rings to the
Interaction Point. Beam-beam deflections scans and their impact for beam-based
feedbacks are considered. A transverse kink instability is studied, including
its impact on determining the luminosity-weighted center-of-mass energy.
Polarimetry in the extraction line from the IP is presented, including results
on beam distributions at the Compton IP and at the Compton detector.
