  We have performed a series of N-body/hydrodynamical (TreeSPH) simulations of
clusters and groups of galaxies, selected from cosmological N-body simulations
within a $\Lambda$CDM framework: these objects have been re-simulated at higher
resolution to $z$=0, in order to follow also the dynamical, thermal and
chemical input on to the ICM from stellar populations within galaxies. The
simulations include metal dependent radiative cooling, star formation according
to different IMFs, energy feedback as strong starburst-driven galactic
super-winds, chemical evolution with non-instantaneous recycling of gas and
heavy elements, effects of a meta-galactic UV field and thermal conduction in
the ICM. In this Paper I of a series of three, we derive results, mainly at
$z=0$, on the temperature and entropy profiles of the ICM, its X-ray
luminosity, the cluster cold components (cold fraction as well as
mass--to--light ratio) and the metal distribution between ICM and stars.
  In general, models with efficient super-winds, along with a top-heavy stellar
IMF, are able to reproduce fairly well the observed $L_X-T$ relation, the
entropy profiles and the cold fraction. Observed radial ICM temperature
profiles can be matched, except for the gradual decline in temperature inside
of $r\sim$~0.1$R_{\rm{vir}}$. Metal enrichment of the ICM gives rise to
somewhat steep inner iron gradients; yet, the global level of enrichment
compares well to observational estimates after correcting for the stars formed
at late times at the base of the cooling flows; also the metal partition
between stars and ICM gets into good agreement with observations.
