We have been discussing the idea of investing a bit extra to get a place that would work to rent out while having minimal to no shared common space (duplex, ADU, separate entrance). 

They used to charge an entrance fee, but Fidelity National Title and their other sponsors allow them to make it free.Who knows? 

We have a phone line for our entrance gate access.

The addition has its own entrance, but also has a connecting door to the front of the house.

I can do this because of the Entrance/Exit Strategy I use.  

Upstairs has separate side entrance to the stairs.

Would her comfort level be different if the ADU had an entrance of it's own that did not share the same yard or driveway? 

Make sure nothing blocks any entrance or exit.  

(no storm door) to give the entrance a bit more elegance.  3) Yes, on the new post4) I would do shutters on all the windows. 

What if you had an emergency (e.g. their unit was leaking water into downstairs), you were out of town, and the handyman/contractor you sent there was refused entrance by this difficult tenant?