  Using 88.9 million BB events collected by the BaBar detector at the Y(4S), we
measure the branching fraction for the radiative penguin process B -> X_s gamma
from the sum of 38 exclusive final states. The inclusive branching fraction
above a minimum photon energy E_gamma > 1.9 GeV is BF (b -> s gamma) = (3.27
+/- 0.18 (stat.) +0.55/-0.40 (syst.) +0.04/-0.09 (theory)) 10^-4. We also
measure the isospin asymmetry between B^- -> X_s ubar gamma and B^0bar -> X_s
dbar gamma to be Delta_0- = -0.006 +/- 0.058 (stat.) +/- 0.009 (syst.) +/-
0.024 (B^0bar / B^-). The photon energy spectrum is measured in the B rest
frame, from which moments are derived for different values of the minimum
photon energy. We present fits to the photon spectrum and moments which give
the heavy-quark parameters m_b and mu_pi^2. The fitted parameters are
consistent with those obtained from semileptonic B -> X_c l nu decays, and are
useful inputs for the extraction of Vub from measurements of semileptonic B ->
X_u l nu decays.
