I listed the questions with my answers. Are the answers correct? Thanks.

Question

A railroad locomotive is a rest with its whistle shrieking, and then it starts moving toward you.

a.) Does the frequency that you hear increase, decrease, or stay the same?

The frequency of the waves increases as the waves are compressed in front of the locomotive.

b.) How about the wavelength reaching your ear?

The wavelength is compressed, producing a higher sounder heard.

c.) How about the speed of sound in the air between you and the locomotive?

The speed of sound is a constant, so it does not change.