No leases, repairs needed, newbie to buy and hold

[Steven Rosenblatt]

I have a 9 unit property under contract and it is currently all rented with reasonable income based on the condition. My question is, the current owner does not have any leases and very minimal security deposits. Should I settle on the property 1st and deal with this myself? Or make the current seller obtain leases. Other notes: a few of the tenants appear to be less than desired, neglecting their pets, potential hording disorder that over flows to the exterior of the building. I am also planning to do some major exterior improvements: roof, siding, windows, HVAC upgrades, and deck repairs, and bring the building and units up to current market standards. This will raise the rents too and possibly turn off some of the current tenants making them want to relocate. Any thoughts on a strategy to tackle this project in a reasonable and fair way?