Guinea pigs require a basic diet of quality hay, pellets and vegetables will keep your cavy healthy. Large cages work best as their housing. Weigh them weekly as this is a good indicator as to whether they are having any problems.
My daughter raised several of them as a child and they lived about 6or7 years. She fed them pellet food, lots of veggies,such as lettuce and always had a fresh supply of water available to them. She kept hers in a medium cage in her room