More up-to-date data can allow you to be one of the first individuals to reach out to a lead.

If I allow the recently received funds to apply toward the most-recently due payment (B), then what happens with the older payment (A) that was never made?

Historical financials allow you to cross-check your numbers against the seller's and understand the discrepancies.

Will brokerage allow?

Also, a good CPA to help you set up your books with allowable expense categories and to answer specific questions.

Other options I would consider is renting each individual rooms (this generally increase the monthly cash flow vs renting to a single person).

Not every municipality will allow ADU's.

I Know it will complicate taxes  because we have to file as an individual and then for the LLC  but there is a fair amount of depreciation and carry forward losses for us to consider, not sure when those will be completely written off. 

Will they allow you to receive direct deposit?

Start with calling the planning dept at the city to define the zoning and allowed density 2.