Normally, once I get it rented I have a cash flowing property that has provided 30% - 100% equity.To your point, I am seeing that some new construction is on sale right now and I am starting to consider them because of the lack of maintenance needed.

This may be able to work if the ADUs can be added at a low enough cost that the NOI and cap rate provides a value high enough to justify the effort and risk.  

They could provide valuable assistance in this matter.

But if you are expecting them to do any of the work for you, i.e. walk properties with you showing you things to lookout for, providing contractor lists, setting a rehab vision unique to that property and market to maximize your ARV... well, I have never seen a guru or course do this.  

And that's OK provided they bring in an accountant, and perhaps one with subject matter expertise in the partnership.

Essentially Airbnb and VRBO will contact the guests, explain what is happening and provide the link to the new listing and they MAY rebook. 

If you have any doubt about it being occupied or not you could put a notice at the door and say that its your property and that you will enter on a given date.You probably should provide a phone number so people may  call you. 

The reviews are tied to the agent because he or she is the person that provided the service.

We provide dark grey washcloths in every bathroom for just that purpose.

A few suggestions/thoughts:- Ask your agent to provide you recent sales (last 12 months) of deals that would have met your criteria, starting with deals they were the broker on.