Hi Jerry,
Nice looking tank!
There are many links with all kinds of data to answer your questions. I tried to compile some of the most used cardstock into some PDF.
Here is a link to my thread.
Cardstock Property Tables and Terms
The first PDF shows Basis Size and also Thickness table.
The 2nd deals with Equivelant weights of cardstock.
The 3rd will answer your laminate questions.
The 4th was done to find the strongest lightweight of cardstock to use for my airplane models.
Hope they help with most of your questions.
Best regards,
Mike Bauer