Answer:
I come with a train and go with a train and the train doesn't need me but can't go without me.
I am quick when Iβm thin. I am slow when Iβm fat. Wind is my worst nightmare.
What tastes better than it smells?
What is black when it's clean and white when it's dirty?
I go from house to house a messenger small and tight. Whether it rains or snows I sleep outside at night.
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?