What color in the visable spectrum is bent the least?

Red bends the least. If you look at a prism with a beam of light shining through it, you will see violet is bent the most. This due to the refractive index of the glass changing the wavelength.

Velocity & frequency are components of wavelength. So the refractive index is a ratio by which the speed of light is changed.

I am not sure if frequency is changed.