You have recieved very sound advice here and if vet school is your ultimate goal, I would suggest you seriously consider what @Calpurnia has said. Not only should living sentient beings not be used as a means to an end, ethically (and ethics are a huge part of being a vet) but schools will not be interested in pet experience in amateur and uncontrolled environments. It sounds like this breeder you are consulting is being very generous. If he is recognized in the community as a reputable breeder, and will take you on as a volunteer and mentor you, that would be a great way to experience the benefits you are looking for while minimizing the risk.