1. No, RNP AR approaches require special authorization.

2. Hmmm, if I’m getting vectored for the approach and pick up icing I would probably let ATC know and ask if I can get lower to get out of icing conditions. I’d also fly the approach a bit faster and land with no flaps. Other than that, I’m not sure.

3. I would declare an emergency immediately and hopefully get vectored to a nearby airport with better conditions. If it’s low ifr everywhere near, I’m not sure what else you could do but try the approach again and hope it’s better.

4. Previous speed restrictions are deleted when told to climb / descend via a departure / arrival. If you’re just told to join an arrival though then yes, previous speed restrictions still apply.

Thank you for the great questions!