How do I get the phone numbers of the owners of the properties?

With this route you can purchase a turn key property and expect to lease the property immediately or purchase an existing rental from an investor that doesn't require rehab and has strong numbers. 

Can they prove how long it takes to rent a vacant property?

Just because the property can close in an LLC with a DSCR loan, does not mean the loan is made to an entity.

I'm a property manager, and I also buy/sell property.

Quote from @Avani Patel: Hello, it is really time consuming for me to analyze each property by manually entering its data to calculate the return. 

Quote from @Louis Hamilton: The property is worth around 800,000 and has no mortgage on it.

I would also purchase the property and not the LLC unless you are a seasoned investor with a good attorney.

., HVAC tune-up, plumbing fixes)Deep clean entire property pre-listingEstimated Cost: $5,000Total Estimated Renovation Cost: $145,000Project TimelineWeek 1-2: Planning and DemolitionFinalize design and materialsObtain necessary permitsBegin demolition (kitchen, bathrooms, floors)Week 3-5: Structural and Major InstallationsInstall new cabinets and countertops in kitchenComplete bathroom tiling and vanity installationRefinish or replace flooringWeek 6-7: Painting and FixturesPaint interior and exteriorInstall lighting, hardware, and plumbing fixturesWeek 8: Finishing TouchesLandscaping and curb appeal updatesDeep cleaning and stagingTotal Timeline: 8 Weeks*This link comes directly from our calculators, based on information input by the member who posted.

Doing so will help you avoid capital gains tax if you decide to sell later.Second: Test it out by renting the property for a year.