The ice caps in the North pole of Mars compose of frozen water and frozen carbon dioxide and the ice caps on the South Pole consists mainly of of frozen water.
Frozen. In glaciers and icecaps.
2%
Frozen in the icecaps (in the form of ice at the poles).
Easy, its tap water! ----
The current - 2014 - estimation is about 70%.
water
There is approximately 1,386,000,000 km3 of water on Earth, which includes all the water within the oceans rivers, lakes, groundwater, atmospheric water, and frozen water (i.e. snowcover and the icecaps).
The poles on Mars are primarily white in color. This is because they are composed mostly of frozen carbon dioxide (dry ice) and water ice. The combination of these frozen substances gives the poles their distinctive white appearance.
Ocean
According to NOAA: "Of the three percent of the water that is not in the ocean, about 69 percent is locked up in glaciers and icecaps. Ninety percent of that frozen water is in Antarctica and about nine percent covers Greenland."
Yes, most of the fresh water is usually stored in the iceberg and icecaps.
No planet is composed of mainly frozen water; Mars has probably the most frozen water of all the planets after the Earth. However, older textbooks and teacher's notes may well refer to Pluto, which is now classed as only a "dwarf planet" and is composed of roughly 50-70 percent rock and 30-50 percent ice. So, although Pluto has a lot of ice, it has more rock than ice (frozen water).