So it behaves in its own unique ways. 

Unfortunately it does seen like this property is very unique so it would be unlikely that you would be able to comp exactly "like items" in this case. 

It might cost you more in profits on this one property to go pure hard money, but it could also prevent you from using a combination of cash, your HELOC, and hard money to purchase multiple properties with more total profit.

So this could be a combination of “place for her to live initially, rental in a few years when she buys her own place, inheritance down the road”. 

Pay interest, give them equity, a combination of both.

It is an "equitable right" of EITHER party when damages will not be good enough (inadequate) or the item is unique.

If you combine the fact that last year was the biggest since 2007 (seems like a familiar year) and that 2020 is on pace to meet/exceed 2019 number in permits approved (also per City of Champaign's discussion of major funding needs here - see page 10 where they expect 20% growth in permit fees through 2023) I believer we're looking at a challenging few years/decades. 

We actually put effort into the interior design and - within reason - open up the floor plan, update kitchens and bathrooms and spend money on landscaping.The goal is always a combination of looks, durability and cost effectiveness.

Also I really want to have unique pin codes automatically generated and sent to guests.

One unique thing to look at and if the new deal works for is do 1031 with the sponsor.