We prefer they use our lease (less vague than existing belonging to property management company running the show currently).

It does sound fishy and it's too much liability for you to accept his belongings.

I would reach out to the son and offer condolences, then ask how he would like to proceed with his mother’s belonging and clean up.

If i am not mistaking, Landlord is responsible to provide drinking water, functional plumbing, cooking Stove, and heating.

I know in the area of PA where i invest, there are a lot of "Alley Ways" that belong to the town, and not the owners of the properties next to them, but they can be used by the property owners as a walk or a drive. a lot of times these areas are just grass, but it may just be listed in your title that you have the right and your neighbors to use it and you can not do anything on it. but also keep in mind that it may come into play if you ever decide to add on to the house, you may have to build to a setback from that easement line.

I asked the tenant (via email) if the dog belongs to her parents who were in town visiting.

He started moving his belongings out eventually, slowly.

I don't think Newark is a sure thing but I think long-term buy and hold investors should be long Newark. 

It is important to understand that only your belongings without a beneficiary go into a trust (most of the time).

I also belong to an Angel investor group that "syndicates" investments in early stage companies.Not sure what an investor would be willing to pay for a service such as this, but I am sure the return would be higher if we can participate as equity partners in the deal.