If you do decide to purchase a primary, a multi-unit property could be a solution in terms of receiving cash flow on the other rented out units. 

I don't think there's a single app that will both run the numbers for you in terms of deal analysis as well as handle your bookkeeping for you.

There is some nuance there that your accountant can assist with but in terms of asset protection truthfully nothing to be gained either way.

Of course, if all three agreed to the change in terms, that would be the easy way out for everyone.

I want to get a “checklist” of what I need to do next in terms of the legal side and paperwork to get this thing rented out (or even steps I need to take prior to renting it out, such as getting insurance and a contract agreement).

I work in Real estate and have broad experience helping expats and investors to find the best properties that suit their needs. 10 years ago, anything you could buy was a great investment, in terms of return, valuation, and resale opportunity. 

I recently was finishing a rehab that in terms of budget was my worst ever (not ideal at my experience level but shows even those with experience have learning opportunities) but was still feeling generous to a local newbie.  

I have a very similar structure in terms of LLCs, property manager, etc with my own properties.

Anything the HOA can do in terms capital improvements to lower the rate?

The biggest change in terms of lending programs id say is fannie's changes to allow for 5% down for 2-4 units.