Their combined income is below $100K per year.

Even creating a simple model to evaluate potential deals or predict returns could be a fun way to combine your interests while gaining hands-on experience.The most important thing is to start somewhere.

Any advise on adding washer/dryers is a plus I know routing new drains can be tricky when trying not to get to invasive on a "cosmetic" job.

Their customer support is terrible and some of their software, but they have about 8x the site traffic in general than Airbnb and VRBO combined, surprisingly.  

As you mentioned, it might be difficult timing the sales of each of properties where you can achieve a combined exchange (multiple properties into 1 property / or a few properties).Just a quick note that may be helpful - I work with a group of investors that can help with a combined exchange into a single property and will buy it back once you've found a replacement propertie(s) as the final destination for your capital.

The primary requirement is that the expected rent would cover the mortgage on the home - and that expected rent is typically determined by a combination of the appraiser and some service like airdna (a site which determines fair market rent).

If you're able to save $50-100K per year for 14 years (when you're 40), a combination of getting solid deals, paying down debt, and having a target goal of income vs expenses, it's definitely doable.  

They are either a combination of a Maintenance/Tenant Management business or Accounting/Real Estate sales/Tenant management service. 

Property details: 3 bed 2 bath both sides with attached garages, aluminum siding, copper plumbing, 1972 construction, separately metered, all electric water heater, range, dryer, public water and public sewer on a slab foundation in a great school district right next to brand new construction everywhere.

Don't forget to account for the cost of the appraisal or any other vendors...an appraisal and survey will over $1000 combined, for example.