Ask the camp director. Some camps have soda machines available to campers and some don't. Campers hear from their family and friends through the mail. Mail is delivered to you once a day. Parents like to read your letters as much as you like getting letters from them.
Camps differ in their telephone rules.
Check with the camp for more information. Just about everyone experiences different feelings when they are at camp, especially when they think about home. These feelings are normal. When you go to a new place it takes a few days to adjust. Yes, one good book about overnight camp is Off to Camp by Myra Pravda and Jeanne Weiland.