You'll need to foster multiple relationships to have a plan B and C contractor handy anyway.Relying on someone else's pictures is not a good idea, even if you're the pro in doing repair estimates.

There are multiple ways for him to get water, he has a 2.5acre lot bordering 2 other city owned streets (my lot is only .24).

At the moment i have multiple options, combined i only have about 4k in capital between my wife and I to use. 

Before engaging with Airbnb rentals get legal advice and do your research.

Additionally, when you create your listing on cozy, it is actually posted to multiple websites making your life easier. - https://www.zillow.com/rental-manager/   - I'm sure you've heard of Zillow.

Multiple offers on most properties. 

My advise would be buy more than a 4 plex - go with 5 and over if you are going with multiples to cut out some of the competition.   

I would start with a Independent agent with multiple markets (companies they represent) and have them shop it for you. 

Also if you are doing flipping, in which case I suggest you look into Series-LLC and you operate each flip in its own child-series (if not clear why, ask for more details).I spent numerous hours researching from multiple sources the whole LLC question and asset protection matter and all the rabbit holes it opens.

I think tax liens as an engagement device is good.