These are professionals with additional training and a stricter code of ethics.

If there is hold over and the property is not available for the new tenant, what kind of legal or ethical responsibility do you have to the new tenant?

It's a smart business decision, but lacks ethics. 

Under capitalization, lack of knowledge, lack of experience, lack of a willingness or ability to learn new things, lack of work ethic, lack of vision and any number of a hundred or thousand reasons.But, one common trait that belongs to all of the truly successful is to know their strengths, weaknesses and limitations; know when to get help and how to leverage the efforts of employees and outside contractors.

You mentioned separating the businesses for tax purposes and that would make sense to as a way to clarify which properties are being held out for rent and which are immediately on the market for resale and the ordinary vs. capital tax treatment differences as well as the depreciation differences.

Talking to references has been the most helpful for me to learn more about an applicant's history of paying rent on time, their treatment of the property etc.

These are professionals with additional training and a stricter code of ethics.

There is a place (a lucrative place even) in rough areas for ethical landlords that spend $ to make a nice place for someone else to live, for sure.

These are professionals with additional training and a stricter code of ethics.

You're taking a number of legal steps that while in and of themselves are not illegal, they are designed to afford you preferential tax treatment outside the letter of the code.