re: I wonder what is the temperature of this ice.
At this lattitude, mean annual temperatrures are around -60 C (that's -76F). Not much "water", I suspect...
Nonetheless, it's very interesting to find significant amounts of residual ice within Hellas basin - one of the deepest parts of Mars surface, and with the thickest atmosphere.
(still VERY thin, by Earth standards, but you could parachute a heavier payload into Hellas than most other parts of Mars)