Lease problem for a new property

[Apar Bains]

Hi Guys, I am planning to buy 2 properties in California with a total of 11 doors between them. Each bedroom is rented out individually by the previous owner on a month to month lease. There are no deposits in place. All tenants are up to date with rent. However there is no formal lease in place. It is more like a handshake deal between the tenants and the landlord. Landlord pays for utilities. I want to purchase the properties, set up everyone on a month to month lease, transfer the utilities to tenants and eventually raise the rents and collect deposits.

1. What is the best way to accomplish this?

2. Landlord has offered to help with getting a lease signed before close of escrow. Is that a good idea?

3. If I decide to evict the tenants and start with a new set of tenants, is that a better idea?

4. Any legal or logistics barriers that I should look out for??

Thanks in advance!!