Glue
ANS 2 - More information is needed to give a sensible answer
No, there is no carpet glue in cigarettes.
You could use duct tape to put it together, or hot glue it.
That depends what kind of glue it is. -I would try Goof -Off for removing unknown glue from a carpet.
Carpet glue, the industrial kind.
You can use a spot remover, but it might be better for the carpet, kids, and pets if you use a carpet steam cleaner that uses hot water. This will melt the glue and remove it easily.
Yes, if the oil stain is thoroughly dry. Use a Multi-purpose carpet glue.
You can upholster a cat tree with carpet by gluing the carpet to the tree. Any carpet store will have carpet glue that you can use.
Dip a rag in Goof Off and rub it on the carpet glue, it will soften enough to peel it off.
Difficult to say without knowing what exactly it is.-Name your glue -
It is generally not a recommended procedure. The abrasion of carpet on carpet will cause both layers to wear prematurely. Certain types of glue down carpet can be installed over existing glue down carpet. Check the manufactures installation instructions. I do agree that installing stretch in carpet over existing stretch in carpet is not a good idea.
PL300 will work for that.
Explain what you mean by 'sustainable' -Obviously it will keep carpet down for years.