Weldwood is wood glue. In any case if you're talking about the plastic sheeting just lay it down and staple it to existing floor. Use as few staples as possible. The nail strips are higher than the floor so you will have to use extra molding to hide them, I think a few staples is a lot easier.

no do not attach your underlayment with any fasteners your laminent floor is a floating floor youll void the warranty for faulty instalation and if the floor cant float its likely to fail instructions are in every single box of laminate flooring you should open a box and read them before you begin personally your original floors are much more desirable and more valuable in that the laminate as a composision of cardboard and glue and is waterdamaged simply by mopping it and it does have strict rules of installation your welcome (in advance)

I am going to install laminate over the pine wood, and there is an underlayment between, I am wondering ,should I NAIL the underlayment to pine wood? or just spread underlayment over the wood WITHOUT any nailing? anyone knows please give me a better solution, thx. BTW, it is for basement.under pine wood, it is concrete.