1.
답다 describes something with traits that are usually associated with the thing itself. e.g. you can describe a man as manly by using 남자답다 or an elderly person as old using 어른답다.
스럽다, on the other hand, is used to show contrast between the thing it describes and their actions. For example, if a young person was rather mature, you could say that they are 어른스럽다. A young person is usually associated with immaturity but in this exceptional case, this person is not immature.
2.
답다 is often attached to concrete nouns like man (사내) and masculine (사내답다) or teacher (선생님) and teacher-like (선생님답다).
스럽다, on the other hand is often used to make adjectives with abstract nouns like peace (평화) and peaceful (평화스럽다) and whim, caprice (변덕) and unpredictable, capricious (변덕스럽다).

