I generally prefer to go it alone, any kind of partner (even relatives) mean you have less say in management, operations and exit strategy.

You can get in hot water that way legally as all LLCs could be argued to be operating as a single entity and thus pierce the corporate veil.  

I’m not too keen on the fund and grow model operating solely on business credit but it does seem the most direct way to utilize the cash I have on hand and acquire enough operating capital to get into decent property.

First off, they are operating illegally under Florida Statutes Section 718.112(2)(a)(1.) by only having three board members (unless there is less than five total units in the condo itself). 

Multifamily properties are valued based on the property's net operating income. 

Do I create an operational agreement between LLC A and LLC B for such operations?

You as the operating partner are responsible for the management of the property: finding tenants, maintenance, overseeing and organizing the financials, etc.

Adding a heating and cooling system (the reason this house was not operational), and minor interior renovations.

So for folks who aren't that, put them at Nursing Station 37, a "it's nice to have someone here, but operations aren't crippled if someone isn't here."

Those are great places that will give you opportunity to speak with operators.