Replying to Rail building questions

I am going to build a rail in Alaska and I had a few questions:
1- Will PVC shatter at low temperatures even if it is thick?
2- If i were to build a single hand rail would i be better off with a steel pipe welded to posts or single PVC screwed to a long 2x4 with supports?
3- is shotgun preffered to single? ive slid both but i rarely ever see a single handrail on here
4- how well does steel slide?

If anyone can answer me these questions it would be greatly appreciated. any extra advice would be great too! thanks for the help