Maintenance - I have an on-call plumber and electrician and a general maintenance man, who'll I call when needed.

My family member will manage any repair calls, maintenance, etc.The family member is open to me renting the property from them for 2400/month and is okay with me listing it on Airbnb.

Find a boiler service company in you area and talk with them about preventative maintenance.

In doing my research it seems that every major company I come across has some type of  issue everyone complains about whether it be poor communication, terrible as filling maintenance requests, or just being unprofessional. 

You will need good housekeeping and repair/maintenance folks as part of your plan. 

Lots of details here to consider so when you say how would I draft this up - there is a lot to consider but my thoughts:Rent = 1200/month3 yr option to purchase = $240,000not sure what state you are in but propose to handle everything (maintenance, repairs, etc and if that is not legal/possible you could do a Land contract or contract for deed with a  minor risk since he has an underlying mortgage).feel free to reach out and schedule a  call. seems like you have a fascinating one. 

Manage all maintenance requests thru the app, so it's nice to not have to deal directly with the tenants or having them call up my mobile.

Turn washer spin speed up to the highest setting because they're unlikely to change it..5 GPM aerator on bathroom faucets1.25 GPM aerator on kitchen faucet1.25 GPM showerhead1.28 gp-flush toilets--I'm only replacing them because they're the horrific 90s toilets that clog CONSTANTLY, as the water savings will literally never pay offNew tub spout diverters because the current ones leak around the edges badlyY-splitter on top load washing machine to connect the washer only to the cold supply (it's not a high-efficiency, so it cleans well at any temperature) Smart thermostat with 74 degrees minimum cooling temp and 71 degrees maximum heating temp until 10 pm, dropping to 68 degrees until 6am Alarms on doors and windows that alert me if either is left open while the heat or AC is onNew windows, because the current ones are single panes in need of heavy maintenance and are already causing problemsPossibly solar screens on two of the windows that get the most light, particularly a west-facing one

Maintenance, small repairs, consumables Internet: $100 / month? 

The biggest issues we faced was equipment breakdown as customers routinely abuse the equipment  the most common repair ws due to over stuffing the washers and using the washers to dye items.