  We present IUE spectrophotometry and optical spectropolarimetry of the
ultraluminous, extreme FeII-emitting QSO IRAS 07598+6508. We find broad
absorption troughs from high- and low-ionization species, showing that this
object is a member of the class of rare low-ionization BAL QSOs. Compared with
non-BAL QSOs, the spectral energy distribution is reddened by E(B-V) sim 0.12,
and the Halpha/Hbeta ratio even more reddened with E(B - V) sim 0.45. The broad
emission lines are unpolarized. We see broad Na I lambda5892 absorption in the
unpolarized continuum, but not in the polarized continuum (at the 5-6 sigma
level). The polarized continuum rises smoothly towards shorter wavelengths with
F_lambda propto lambda{-2}. We argue that a normal QSO continuum is polarized
by scattering from a region within, or very near, the Broad Emission Line
Region (BELR). Thus there are at least three distinct light paths to the
observer: a dusty path from the BELR, a direct path traced by the unpolarized
continuum, passing through dust and low-ionization gas (NaI), and another
relatively unobscured path followed by scattered continuum. This provides
direct evidence that a BAL region and dust only partially cover the central
QSO.
  Ultraluminous AGNs, including IRAS 07598+6508, appear no more IR-luminous
than non-IRAS-selected QSOs, and have normal L(IR)/L(opt) ratios when the
optical luminosities are corrected for reddening. Reddening and BALs occur only
along some sight lines and the parent population of BALQs are `normal' QSOs.
