It is important to keep your feet warm and dry as possible. It is worth investing in strong hiking boots which have good waterproof qualities. If you can, finger a bit of waterproof wax around all the material and stitching on your boots.
My workshops trips in October and November had something in common. On both trips, I saw one of my cameras give out an error message before dying. Both times, I had to send the camera to a registered service centre for repair.
Coastal landscapes are very effective long exposures because they often give the photograph a strong contrast between the temporary and the permanent.
This article discusses tips for shooting against the rain or waterfall spray. Both are common issues when you are shooting against the wind near waterfalls or angry beaches in Iceland.