What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

Professional property managers stay updated on legal requirements through memberships in state or national organizations.

(larger would require fire sprinklers). 

Additionally, lenders may require a release price (a specific amount to pay down the loan) for each property sold, which can complicate the strategy.It’s worth discussing these details with a trusted lender or mortgage broker to ensure the plan aligns with the loan’s terms.

It is more complex and has added requirements such as a formal set of books just like a corporation. 

Wait until it's close to the end of his lease (know what the law requires) and then give him notice that you will not renew.

If you don't have a key, change the doorknob to an appropriate interior knob that doesn't require a key.I provide my tenants with keys to all doors.

If the property does not require an extensive rehab and just needs cosmetic repairs then a standard landlord dwelling policy in most cases depending on the carrier.

Now many escrows will require that the seller sign off on the EMD release, which can be frustrating since most contracts say it should be a unilateral function (buyer automatically gets their EMD back if they cancel within the option period), but if a seller chooses to be a jerk and not sign it, the EMD could be frozen in escrow, so don't use your rent money for it. 

., as Chris noted, the required documentation will be outlined in the LP Agreement you signed.