can I use white glue to glue this to foam insulation board? How easy is the mat to cut?
You probably could use white glue, but it will take forever to dry on styrofoam because it can’t soak in. Caulking, Liquid Nails for Foam, or a water-based contact cement might be a better choice. Just make sure the adhesive you choose is safe to use on foam.
The first and only time I attempted to use a grass mat, it tended to wrinkle and curl up on the edges as the adhesive dried. WS has a new, plastic-based mat which they claim can even be formed into hills, but I have not seen or tried to use one of them.