  One of the primary goals when studying stellar systems with neutron stars has
been to reveal the physical properties of progenitors and understand how
neutron star spins and birth kicks are determined. Over the years a consensus
understanding had been developed, but recently some of the basic elements of
this understanding are being challenged by current observations of some binary
systems and their theoretical interpretation. In what follows we review such
recent developments and highlight how they are interconnected; we particularly
emphasize some of the assumptions and caveats of theoretical interpretations
and examine their validity (e.g., in connection to the unknown radial
velocities of pulsars or the nuances of multi-dimensional statistical
analysis). The emerging picture does not erase our earlier understanding;
instead it broadens it as it reveals additional pathways for neutron star
formation and evolution: neutron stars probably form at the end of both core
collapse of Fe cores of massive stars and electron-capture supernovae of ONeMg
cores of lower-mass stars; birth kicks are required to be high (well in excess
of 100 km/s) for some neutron stars and low (< 100 km/s) for others depending
on the formation process; and spin up may occur not just through Roche-lobe
overflow but also through wind accretion or phases of hypercritical accretion
during common envelope evolution.
