Inquire about the impact on the properties from the most recent flooding in the area (Dec. 2015).

That will have an impact on your cash flow.  

However, like @Russell Brazil pointed out, there mostly likely is not another RE bubble around the corner and whatever bubble is out there will not have a dramatic impact on RE prices, at least nationally.

If so, what impacts do you think it will have over your long term profitability investing in markets with weaker demand and greater supply relative to that demand?

Very generally speaking, does the fact that another tennant would be sharing the property negatively impact the amount of rent  I can collect on the main 3/2 - if so how much?

Bill and Kim will never know the impact they’ve had on our lives.

It is inevitable that you will make some mistakes along the way, just be educated enough and monitor your risk to minimize the impact of those mistakes.

Ladders, impact bit set, led light bulbs, angle grinder, toilet.  

There is a Pilot gas station about 120 ft (slight up gradient) from our property, and our environmental phase 1 shows there was a spill in 2011.

The thing I want you to understand is that $10M is not very much money as it relates to wealth, and specifically not if you project it forward and experience the impacts of inflation.