I havent kept many frogs, only one to be exact, and the whites tree frog was it.. I agree they are fairly hardy pets =) They can grow to be quite large though, I think the size of a fist for either males or females I'm not positive..
No darts are not very good for first time pet owners. They require specific care and feeding and are very delicate because of their small size. Also they are a not to handle pet, they are more of a viewing one.