Knowledge compounds. 

Look into taking over the debt "subject-to" as @Sean Wait mentioned.I'll bow to @Tim Swierczek's knowledge on assumables, but another tactic to consider is a "wrap mortgage".That is part of an owner-financed solution that leaves the existing debt in place (if the seller will allow!) 

Hey Hunter, I'd personally pick one market to focus on.The reason is simple... compounding benefits.

I was told that they'll likely be looking for 8-10% ROI, not sure if this is compounded annually or if it would be a simple interest calculation...these are some of the nuances I need some direction on.- What should the length of the investment period be?

If not installed properly the lower walls could bow out and cause a collapse.

Warren Buffett's biggest lesson in investing was compounding, and the immense value it has in the long term.  

The best you could hope for in that case would be selling in a hot Spring market where some/all of the inspection is waived by the buyer.I'd be happy to process more with you, send some good contacts your way, or bow out.

You'll never build compounding returns on your knowledge, relationships, connections, deal flow, etc. by jumping from one market to the next.You'll be able to do all of that by staying active in one market over several.But again, if it no longer makes sense for your goals... that's the time to start thinking about a different market.

I also backed out of a $350,000 property that the inspector caught that the walls were bowing in on themselves.

Over the long term and compounded, it can look like a lot more.i.e. 2% growth over 20 years