1, is the universe going to be different if neutrinos do not have mass?
At some scale, yes. As this requires for instance physics beyond the Standard Model to be explained.
2, Why is it that only charged particles has the abilities to emit cherenkov in glass and neutrinos cannot
Neutrinos do not interact electromagnetically. In other words, they do not interact with photons (or light).
Now that I find the most interesting about these lil fellas
That indeed makes them the most weakly interacting particle of the entire standard model :)