how does air/glass/water slow down light?
It doesn't really.. light speed remains the same. However, photons are absorbed and re-emitted on the way through the medium and it is the time that this takes that makes them appear to travel slower.
Why are they absorbed and re-emitted? How?
Basically photons carry a certain amount of energy with them. Electrons bound to an atom (not free electrons) will be able to absorb this energy and fly up an energy level or two. When they go back down they will emit a photon.
Question, does the index of refraction reflect colors of different wavelengths differently because the latice structure of the compound? Also, how come there is no light that goes straight, or is there just a tiny amount due to probability of not being scattered.
Light moves "straight" through a vacuum.
Why is it then re-emitted in the same (or opposite, whatever you want) direction that it has been absorbed?
Conservation of momentum.
Rather than repeat everything that has already been discussed, may I point to an old string with almost an identical question?
Separate names with a comma.