"As we move through the visible spectrum of violet, blue, green, yellow, orange and red, the wavelengths become longer. The range of wavelengths (400 - 700 nm) of visible light is centrally located in the electromagnetic spectrum (Fig. 1)."
-https://www.asu.edu/courses/phs208/patternsbb/PiN/rdg/color/color.shtml
We all know, Density = Mass/ volume.
When volume increases and the mass remains the same , the density will decrease considerably.
All the energy goes into melting the ice. Ice and water are <em>at equilibrium</em> during melting, so the temperature does not change.
Once all the ice has melted to water, the temperature will rise.