I don't know what the previous owner used but whatever it is it is on there.
In the past I have used a utility knife to cut it, but I have seen people use everything from exactos to turkey carvers. to attach it I would probably use the 3m spray adhesive that most uposltry shops use (and is available at home depot as well as just spray adhesive).
you can buy the foam in different thicknesses too.
cool im gonna look around my homedepot tonight... it sucks since i live near the ghetto our home depot has NOTHING i ever need. so i will probably walk around for an hour looing for this stuff then give up and buy drill bits or 10mm wrenches or something i have 90 of but can never find when i need them.