Installing new carpets

I have been working on a 66 Barracuda (20+ years now) but I am now getting ready to install carpets. Already purchased the carpets but have a couple questions for anyone who might have undergone this task.

1. I know there was a cardboard lining that went under the carpet on the back of the back seat - any suggestions on what to use to replace that, where to find the material etc.
2. Same as the first only for the main deck section in the back.
3. I don't remember there being any gluing except for the side wheel wells, but was wondering about the back door to the trunk area - was that section of carpet just held by the hinge and then also the trim around the outside edges or was glue also involved?
4. From experience is there a suggested sequence of which pieces to install first second third etc, and also best procedure for marking and cutting for auto floor shift as well as things like the brackets on the wheel wells?

Thanks for any and all input.