If you can find a condo with an active HOA and one that has a healthy reserve and is run well, condos are amazing investments.  

Would like to grow a healthy cash-flow portfolio in the next 5 years to supplement (or completely replace) retirement.

I'm in analysis paralysis... but I think it's definitely necessary for a newbie to calculate and proceed with healthy caution.

Over time, the stock market will provide healthy returns, but it comes with lots of volatility (ups-and-downs).

Even if the roof is falling in it's probably still cheaper to just repair it, all the infrastructure, utilities, surveys, permits, soil studies etc cost a fortune.  

Do you have a proper vapor barrier covering the soil?

If your development consist of individual housing structures, simply calling 411 may suffice.To determine the subsurface soil conditions, you will need a to involve a geotechnical engineering firm. 

Luckily, I've taken lots of photos before we tore the stained & soiled carpet out, so I am doing that today.  

If all of the units are dated, assume a healthy number for regular repairs, and assume at least 1 major and 1 minor appliance to be replaced yearly for the whole building. 

a lot of the bottom and sides of the pool so that water will drain into the soil.