  Near-future experiments intend to detect strong-field Breit-Wheeler pair
creation from the collision between bremsstrahlung bursts containing
GeV-$\gamma$ quanta and high-intensity laser pulses. In this theoretical study,
we investigate the influence of laser focusing, radiation reaction and a broad
bremsstrahlung $\gamma$ spectrum on the energy and angular distributions of
created pairs. Understanding the role of these inherent reaction attributes
provides relevant insights for experimental detection strategies and data
interpretation. We show that the inclusion of radiation reaction leads to a
narrow energy spectrum of the yielded particles, whose maximum is shifted to
substantially lower energies as compared to the case in which radiative energy
losses are ignored. The broad bremsstrahlung spectrum also has distinct
influence on the particle distributions, whereas the impact of laser focusing
turns out to be rather moderate in the considered parameter regime.
