I think new builds don't really work from an ROI standpoint, but if you can find properties that have easy ADU conversions then the value might be there.I'm in MA and we just made ADUs legal by right, so I'm looking into the best ways to add value using them.

Seems like a messy situation. 

So I contacted the tax collectors office and was told there was a legal loophole and that since the building had been owned by a non-profit for part of the year it would receive tax exempt status for the full year.

If you do have to move because of a job, you would be safest (in my opinion, i am not giving legal advice or financial advice), i would sell that property to ensure that you did not just purchase with the goal of moving out early and taking advantage of lower rates and lower down payments for purchasing your home as a primary residence. 

You will want to consult with a lawyer.In regards to your last two questions here's some background on what makes a contract valid and enforceable:Offer: A promise to do or not do something within a certain time period Acceptance: A clear and direct statement that all terms and responsibilities are accepted Consideration: A legal and adequate inducement given in exchange for the promise Capacity: The parties to the contract must have the legal capacity and competency to contract Awareness: A party must be aware of the contract Legality: The contract must be legal in the jurisdiction it will be operating in***Not legal advice*** Steps I would take: -Review contract in detail to understand each counterparties responsibilities (if you are not aware)- Email a copy of the lease to each of the tenants listed on the lease and reiterate lease expectations for termination notice, rent payment etc. - If the lease was signed via Docusign (other esign may have same ability) - you can go to the envelope, go to history and view the IP addresses for each action taken.

Any legal issues I should be aware of in this situation? 

Tax and Legal ConsiderationsUnderstand the tax implications and legal responsibilities associated with rental income.

What happens during periods when the demand for legal work is lower?

This doesn't replace the need for a MSA that will capture additional clauses needed on a Contractor-SubContractor relationship, this is just a project specific form you would use in addition to the MSA (prepared by your Attorney):This template is for informational purposes only and does not constitute legal advice.

I am starting the legal process as we speak and depending how many more we can make this a class action law suit.