We would buy this house all cash. 

You are correct, buying a four plex is tricky here putting 3.5% down.

We went from buying light rehabs to buying major foundation and mold issues to make numbers work until even that did not work anymore.

Airbnb is a company so the only way to buy one would be to own stock in the company. 

Determine what type of property you want to buy - What Zip code, what condition homes, price range, etc.Contact 3-4 realtors that helped buyer agent buy the type of homes you are looking to buy.Then go with the 1 realtor that you connected with the most.

I  Income:  The amount of property you can buy will be dependent on your Debt to Income ratio.  

Investment Info:Small multi-family (2-4 units) buy & hold investment.

Investment Info:Small multi-family (2-4 units) buy & hold investment.

Quote from @Henry Clark: I old look at buying your lumber early.  

Do that for six months before you think about buying so you meet other people who are doing what you want to do.