Most medium weight towels are about 0.1 pounds per (sq feet). The weight of a towel will depend on its quality, material, size, among other factors. Cotton files weigh more compared to other materials.
Depends on the quality and material. I bought a really cheap bath towel once because there was nothing to use for a floor mat (I didn't want to drip all over the floor) and it weighed at most half that of the current towel I have which is cotton.