Do you have to spray the fresh gunite with water so it does not dry out?

Absolultely, after an intitial set you want the concrete to dry at 50% humidity and a temp between 50 to 70 degrees if possible. Proper hydration is key too much water bad concrete too little water bad concrete. Or use curring blankets but be careful here. Best results are to wet down the concrete 2 twice a day for the first 14 days. Dont use too much water, just what the concrete/gunite needs.