@Alecia Loveless is correct--tenants need access 24/7 to their electric service panel, water and heat, assuming those are individual utilities for each unit. 

To minimize capital gains tax on the sale of their primary residence, your in-laws can utilize the $500,000 capital gains exclusion, potentially explore an installment sale to spread tax liability over several years, or consider converting the property into a rental to use a 1031 exchange for tax deferral eventually.

Another option would be to utilize a property manager to manage everything and keep a buffer between you and the tenants.

I underestimated utilities in my early years, so I ensure those are properly captured (electricity, gas, water and trash).

ALTA survey, utility survey, etc.$100k per building, I'd say not usually. 

Did they also do utilities and roads, or was that left for builder? 

There's a few different ways to focus on a lower rate such as with house hacking and making the investment your primary residence, requesting a significant closing credit from the sellers for standard rate buy-downs (which I've had great success with recently), or utilizing lenders who offer short term rate lowering solutions such as 2-1 rate buy downs (again, ideally paid for by the sellers).

There is the Experian Boost that adds monthly utility bills as credit and various apps and facebook groups.

Due to increased rates i did not refi so i did not get opportunity to see how an appraiser valued the half bathroom but the comps with same bathroom count had crazy valuation for the additional half bathroom.Taking under utilized space like a work area to add a br where the added br does not put you above the normal for the area can add value.Similar if a neighborhood is virtually all 3 br and 4 br properties and you find a 2 BR, it could be a value add to add the bedroom via new construction.  

Gave him 10 months free space rent and paid for all his utility hookups.