  The branching fractions of Ds meson decays serve to normalize many
measurements of processes involving charm quarks. Using 586 pb^-1 of e+ e-
collisions recorded at a center of mass energy of 4.17 GeV, we determine
absolute branching fractions for 13 Ds decays in 16 reconstructed final states
with a double tag technique. In particular we make a precise measurement of the
branching fraction B(Ds -> K- K+ pi+) = (5.55 +- 0.14 +- 0.13)%, where the
uncertainties are statistical and systematic respectively. We find a
significantly reduced value of B(Ds -> pi+ pi0 eta') compared to the world
average, and our results bring the inclusively and exclusively measured values
of B(Ds -> eta' X)$ into agreement. We also search for CP-violating asymmetries
in Ds decays and measure the cross-section of e+ e- -> Ds* Ds at Ecm = 4.17
GeV.
