Assuming an existing lease - no deposit

[Melody Xing]

Hi everyone, my name is Melody. My question is that: 

1: I’m buying this rental property, the seller is asking to assume the existing lease but this lease doesn’t have deposit what should I do for now during this buying process and in the future? 

2: Since the lease now is assumed, what documents can I ask the seller to provide about the tenants and what documents should I get about the tenants? 

Thank you guys so much in advance, this is my first time investing rental property. I have so much to learn and thanks very much to bigger pockets.