During the feasibility period I'm planning on conducting the usual due-diligence with a thorough inspection of all the property's systems and structures (utility services, roof, HVAC, maintenance history, lot survey, tenant interviews) along with a Phase 1 ESA. 

The seller drove a real tough bargain during the entire negotiation phase.

How much bare usable ground is there?

My wife and I have built our development business from the ground up and now have 5 employees and a number of contractors.  

The reality is supply demand   and how safe and easy is it to manage the assets.. generally speaking  in any larger MSA the high returns are in areas of much higher risk unless your on the ground.. 

So, try not to get caught up in the market analysis phase for too long!

I would examine those markets to see if the deals would work with what you want to spend because then you have boots on the ground and/or a competitive advantage in that area instead of choosing a town you don't know and building a whole time that are only verified online.

Having boots on the ground is key and there are many folks here that won't have the money that you have.

One of the units (ground-floor) includes the basement in its living space.

I actually took the middle ground and purchased a systems home warranty plan in case it does fail.