Element order of Gauss point data? How many integration point?

Dear all,

I am going to use the Gauss point data to define a material properties. I am confused by the element order of the Gauss point data, say 0, 2, 4,6,8 ,10.... Does these number mean the integration point within an element? If not, how can I know the number of integration points?

Another question is what principles I should follow to select the element order. Now, my PDE is discretized by linear shape function. So, which element order for the Gauss point should I select to define the material properties?

Thank you so much for your help.