Stress analysis in honeycomb panel

[pcomp]

I could spend some time to dig in this forum to model the honeycomb sandwitch panel. Gbor and swcomposites have posted very good informations. Therefore, I decided to use pcomp card with 3 layers (skin,core,skin)in the shell mesh. I use Mat 8 card for core and provide G13 and G23 values as ribbon and transverse shear stiffness of the core.

Now I have the following doubts..
1) What shold be the density of the core?. I feel I should use calculated values by dividing mass of the hobey comb cell by the total volume of the cell including voids. right?

2) How to perform stress analysis of a honeycomb snadwitch panel modeled with 2D shell elements? How do I infer my panel (face skin or core) is failing under certain load? How to report the result of the analysis?

3) My model contain 20 pieces of sandwitch panels, connected by tab and slots as well as strong epoxy glues. With 2D Shell elements can I closly simulate bonding and interface conditions between two sandwitch panels? How to study the bond failure between two sandwitch panels?

Thanks