  We provide atmospheric parameters and rotational velocities of a large sample
(~400) of O- and early B-type stars, analysed in a homogeneous and consistent
manner, for use in constraining theoretical models. Comparison of the
rotational velocities with evolutionary tracks suggest that the end of core
hydrogen burning occurs later than currently predicted. We also show that the
large number of the luminous blue supergiants observed in the fields are
unlikely to have directly evolved from main-sequence massive O-type stars as
neither their low rotational velocities or position on the H-R diagram are
predicted. We suggest that blue-loops or mass-transfer binary systems may
populate the blue supergiant regime. By comparing the rotational velocity
distributions of the Magellanic Cloud stars to a similar Galactic sample we
find that (at 3sigma confidence level) massive stars (above 8Msun) in the SMC
rotate faster than those in the solar neighbourhood. However there appears to
be no significant difference between the rotational velocity distributions in
the Galaxy and the LMC. We find that the vsini distributions in the SMC and LMC
can modelled with an intrinsic rotational velocity distribution which is a
Gaussian peaking at 175km/s (SMC) and 100km/s (LMC). We find that in NGC346 in
the SMC, the 10-25Msun main-sequence stars appear to rotate faster than their
higher mass counterparts. Recently Yoon et al. (2006) have determined rates of
GRBs by modelling rapidly rotating massive star progenitors. Our measured
rotational velocity distribution for the 10-25Msun stars is peaked at slightly
higher velocities than they assume, supporting the idea that GRBs could come
from rapid rotators with initial masses as low as 14Msun at low metallicities.
(abridged).
