What do you think i should get for my rat?

So i'm thinking about getting a rat and i was wondering what i should get for him/her? and also are they really social like should i get two rats? Also how big should the cage be and how often should i clean it? And what toy's should i get him/her like do rat's like those balls that they go in and should i get them him/her something to chew on and are there any treats that i can get them? And last thing should i get on from a breeder or a pet store i was thinking pet store because there cheaper but what is so bad about getting a rat from a pet store? Thanks any answers will help!