You should only test one plant at a time. If there was a bad reaction, like stomach cramps, nausea or headache, induce vomiting. If there are not ill effects eat a couple of tablespoons of the plant and wait another 8 hours. If you need protein you can kill rabbits, birds, mice, fish and squirrels. You may need to trap or snare or spear the animals.
Frostbite is a major problem when hiking in the cold.
To prevent frostbite do not wear tight shoes. You need to be able to wiggle the toes and keep the circulation going. Stay out of the wind as much as possible. Keep your clothing dry. Keep your toes, fingers, arms and facial muscles moving.