Thanks for your answer and tips.
Eventhough we have skied before, we´re not experienced in cross country skis, so I think that´s not a good option.
We´re using snowshoes, and we plan to do more then 25km, despite of the short day light hours. Of course it will depend on the terrain and weather conditions, but we´re aware that´s going to be necessary.
The 9 days you mentioned would be from Akureyri to Hella? In winter? We have a few spare days for setbacks.
I´ll take a look at the south coast issue.
Do you know any store were we can buy or rent the sledges in Reyk?