We've had this property for over ten years and plan to take the equity (via 1031 exchange) and invest into a larger project(s).

Currently, the owner lives in the larger one and rents out the three smaller ones. 

It is a matter of personal choice to use the HELOC.  

I don't think that's the 1st choice of any developer. 

I think that if you have a choice of making it into a third bedroom and private bathroom with its own entrance.

There is no one way and it depends also on how you choose to operate your business.Monthly rent...dependant on property, market drivenUtilities....specific to property and marketsinternet, cable....market drivenTenant or landlord costs.. market and landlord choice

Been considering building a group of 4bed/4bath detached units for student housing, but I'm wondering about the feasibility of building larger units instead.

The best choice we made was performing full inspections, and asking the owners to fix the items discovered.

I buy turnkeys (my personal choice) so I wouldn't bring in extra cash if appraisal comes in lower.

I'll offer to include the cost of moving her stuff (ave cost local move is 2,300) to a storage facility of her choice in town.