The good news is that once you gain some traction you can hire a VA to help with the initial calls (either part time or full ). 

Setting clear expectations upfront with a detailed lease agreement is a must.Consider Property Management: If managing the property starts feeling overwhelming, consider hiring a property management company, even if just for the rented units.

Did they hire out? 

My wife and I just closed on a lake home in Wisconsin and are looking to hire a management company.

I spoke with a sales rep from the Propstream team and they said that their sale price estimates (for non MLS users) are usually within 1% accuracy, but they didn't provide any way to verify that claim.

Some I can think of off the top of my head would be salaried sales reps, basic record of past performance, proper offering documents, back office procedures, policies and procedures for proper vetting of investor accreditation. 

@Hieu Bui Are you planning on doing all the work yourself or hire contractors?

Decide whether to manage the property yourself or hire a property management company.

Hired someone to cut the opening below that window and installed the new AC through the wall.

By virtue of asking this here, it's clear you're weighing the benefits (feasibility) of doing it yourself or hiring someone.