No, the vertices are not ordered. I have another file that says how to put them together to generate tetrahedrons. Every line of this file is made like this:
3 4 2 5
to indicate that the first tetrahedron is made from the third, fourth, second and fifth verteces.
A friend of mine has suggested to me to create, out of Maya, a Python Program to create an obj file from these informations and then to simply import the obj into Maya, I think I'll try even this solution.