Glad you like him mate, i use a uv stable paints and varnish on the heads so it'll last a long time, i wouldn't sit it in direct sunlight though right next to a window for instance, but other than that it should be fine
I leave the heads hollow so you can add them to a body piece, they'll be fine, you can use something like a kitchen roll holder for display, i stuff the heads with a bit of bubblewrap , i'll be making the hands and feet as soon as i can and as i make the lifesize i'll make a thread on what you need