The signing parties are "stopped" from saying anything different after they sign the letter.Each Tenant Estoppel Letter states the attached copy of the tenant lease is accurate and was signed by the tenant, there are no other written or verbal agreements, the tenant has paid rent through a certain date, and there is no prepaid rent other than the current month.

I've heard some rumors of Airdna skewing data a bit (I've heard this first hand and read online.)

Then it is up to your tenants to stop by and deposit the rent money/check in the account by a certain date.  

—----------------------------------------------------------------------------------------------------------------------------Subcontractor Agreement TemplateThis Subcontractor Agreement (“Agreement”) is made and entered into on [Date], by and between:Contractor: [Full Name/Company Name] [Address] [Phone Number] [Email Address]Subcontractor: [Full Name/Company Name] [Address] [Phone Number] [Email Address]Project Details: Project Name: [Project Name] Project Address: [Project Address] Project ID or PO Number: [Internal Identifier, if applicable]1.

It's the basic formula for selling an online course that teaches you nothing you cannot learn on your own.

.: Hi,Is there a way to download specific addresses for houses in a certain area online?

Everything you need to learn/know is available online for free.

This highlights why it is also important to manage lease-end dates. 

There's a self-proclaimed Section 8 guru online who claims he hires random property managers through this website called Thumbtack.

Cold calling is a great idea to get started, but maybe try connecting with local real estate groups or online forums too—they can sometimes have off-market deals.