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...

The town should be able to provide you the use classification of the unit. 

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

The IRS defines a “quality” cost segregation study as “a study that is both accurate and well documented with regard to” 1) the classification of property into classes, 2) Explanation of rationale for the classification of the property and 3) substantiation of the cost basis of each asset and reconciliation of the total allocated costs to total actual costs.

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:)

Don't allow financing or a finance contingency (it can be a good indication they are selling above market value) Don't allow for your own independent property inspection Are not realistic with their pro forma's (i.e. they don't include vacancy or maintenance projections or use unrealistically low vacancy factors) Require you to pay for any renovation upfront Sell only in cheap. low end neighborhoods Don't accurately represent the neighborhood/property classification Don't have consistent rehab standards for all properties Don't provide a scope of work for the property Can't provide references of repeat investors