It passed the septic inspection and another inspection showing that it is functioning great.

It was very distressed, the roof leaked, 1 of the 2 bathrooms was in non functioning, and it came with 2 "tenants" living in trailers that we had to remove.

My goal is to convert the unfinished basement into a fully functioning ADU.

Should I take this out to buy an investment property, functioning like an "all cash" purchase or should I use it as a down payment for a more expensive property and take out a mortgage? 

The time to positive cash flow is mostly a function of how close property is to cash flowing at acquisition and the rent appreciation.  

Unique question but I remember in one of the episodes the guest mentioned they requested a list of water meters/addresses from the towns water department. This requested lists criteria targeted the meters in town that...

We have sheets still in the rotation from 5 years ago and they look the same as the newest ones I put in service last year.

Is it a good, functional rental property insurance?

Depending what you are doing, what you'd like to do, and what you'd need to do, there are plenty of variations of structures and functions ---- kinda like task organizing a task force

Just don't see how several of your questions can be answered in one-line like you say.Example: Talk me through the full life-cycle of a tenant, touching on any fees associated with a particular stage or function (ex: advertising, onboarding, lease, renewal, move-out)BTW - they are great questions:)