no
You survive by using what ever you can find in the forest, to survive.
Yes, snails can survive cold temperatures. The snails will stay out until the temperature turns to freezing then they will seek shelter.
yes
Snails are more active in the dark because at night, it is cooler at night than in the daytime. Snails have to stay moist to survive.
Caterpillars, slugs, snails
All snails need water to survive. I doubt that they will survive lack of water. First, water snails have to live in water, or else they will dry up (I know this from experience, because once my water snails crawled out too much that they crawled out of the aquarium. I found them underneath the dinner table, dried up like un-cooked pieces of macaroni.). I know garden snails will drown in water, but without water they dry out as well, and will go inside their shells and won't come out. So both types of snails won't be able to survive lack of water, in my opinion.
No
They don't need any particular color shell to survive.
1. Please be more specific. How does what help the animal survive in the forest?
Every living creature needs oxygen to survive. Just as every living creature needs water to survive. For example, such as spiders. Yup, spiders do to need oxygen AND water to survive, and of course food. So the answer to your question would be yes, snails do need oxygen to survive.
they hide in their shells and camouflage into the soil and earth