  We present an $r$--band photometric monitoring of the two images A and B of
the gravitationally lensed quasar SDSS J1442+4055 using the Liverpool Telescope
(LT). From the LT light curves between 2015 December and 2018 August, we derive
at once a time delay of 25.0 $\pm$ 1.5 days (1$\sigma$ confidence interval; A
is leading) and microlensing magnification gradients below 10$^{-4}$ mag
day$^{-1}$. The delay interval is not expected to be affected by an appreciable
microlensing--induced bias, so it can be used to estimate cosmological
parameters. This paper also focuses on new Gran Telescopio Canarias (GTC) and
LT spectroscopic observations of the lens system. We determine the redshift of
two bright galaxies around the doubly imaged quasar using LT spectroscopy,
while GTC data lead to low--noise individual spectra of A, B, and the main
lensing galaxy G1. The G1 spectral shape is accurately matched to an
early--type galaxy template at $z$ = 0.284, and it has potential for further
relevant studies. Additionally, the quasar spectra show absorption by
metal--rich gas at $z \sim$ 2. This dusty absorber is responsible for an
extinction bump at a rest--frame wavelength of 2209 $\pm$ 2 \AA, which has
strengths of $\sim$ 0.47 and 0.76 mag $\mu$m$^{-1}$ for A and B, respectively.
In such intervening system, the dust--to--gas ratio, gas--phase metallicity
indicator [Zn/H], and dust depletion level [Fe/Zn] are relatively high.
