Hi pinkannie, I can only tell you second hand of my step daughter's recent trip (only two weeks ago) to Norway to see the Northern lights.
As she and those she travelled with all have their original knees I don't have any information about how easy difficult it would be for you, I'm sure as you say you could get some sort of stick to aid you. I believe the snow is of the crunchy type though it was so cold where she was it just doesn't melt and she actually visited an ice hotel whilst she was there. She has also been to Iceland not to see the Northern lights but on a previous trip in the summer months and apparently it is also an amazing place.
This post is just to say that she saw the lights, she came over last week-end to show us the photos on her phone, they look truly amazing. She tells me it was an almost religious experience for someone like herself who doesn't believe.
Hope you get the information you need from someone else to enable you to arrange your trip, because the experience, I am told, is well worth it.