Can I use it outside?
Yes, Foamex is Water Repellent / weatherproof and does not ingress moisture so it is ideal for external applications. It is warranted against UV fading for up to 7 years outdoors and 10 years indoors.
Is it easy to hang / mount?
As a strong, rigid material, it is easy to hang using self tapping screws, double sided Velcro or double sided adhesive pads. Mounting on Foamex will give you excellent dimensional stability and it may be reused a number of times.