  We study the emission from the hot interstellar medium in a sample of nearby
late type galaxies defined in Paper I. Our sample covers a broad range of star
formation rates, from ~0.1 Msun/yr to ~17 Msun/yr and stellar masses, from
~3x10^8 Msun to ~6x10^10 Msun. We take special care of systematic effects and
contamination from bright and faint compact sources. We find that in all
galaxies at least one optically thin thermal emission component is present in
the unresolved emission, with the average temperature of <kT>= 0.24 keV. In
about ~1/3 of galaxies, a second, higher temperature component is required,
with the <kT>= 0.71 keV. Although statistically significant variations in
temperature between galaxies are present, we did not find any meaningful trends
with the stellar mass or star formation rate of the host galaxy. The apparent
luminosity of the diffuse emission in the 0.5-2 keV band linearly correlates
with the star formation rate with the scale factor of Lx/SFR\approx 8.3x10^38
erg/s per Msun/yr, of which in average ~30-40% is likely produced by faint
compact sources of various types. We attempt to estimate the bolometric
luminosity of the gas and and obtained results differing by an order of
magnitude, log(Lbol/SFR)\sim39-40, depending on whether intrinsic absorption in
star-forming galaxies was allowed or not. Our theoretically most accurate, but
in practice the most model dependent result for the intrinsic bolometric
luminosity of ISM is Lbol/SFR\sim 1.5x10^40 erg/s per Msun/yr. Assuming that
core collapse supernovae are the main source of energy, it implies that
\epsilon_SN\sim5x10^-2 (E_SN/10^51)^-1 of mechanical energy of supernovae is
converted into thermal energy of ISM.
