Presumably not high end neighborhoods, but are there areas to avoid?

Retirement investments generate earnings for your retirement account which is for your benefit later on, presumably in retirement.

My debt to income ratio is also worrisome because presumably it will be more difficult to qualify for a loan post first purchase but this would be mitigated from my understanding if your cash flowing.  

Pulled my personal credit the other day and it said PRESUMED LIVING!

Presuming they did and now are not happy is a red flag in my eyes.However If I have screened the tenant well, I would pay a one or two hundred to have it cleaned.

Presumably, what works for one half would work for both halves of a duplex if you move out, although some duplexes are uneven - one with more sf or bed/bath combos, etc.

The Home Invasion Couple from Hell - even though I have made it very clear that if you smoke, you should not book my room, guests do it making for a very awkward and uncomfortable situation, as they attempt to hide their smoking throughout their stay up to and including smoking by an open window while the room air conditioner is running.This couple also left beer cans throughout my home, presumably when they finished chugging them and crushing the cans on their foreheads.

Depends on whether you can build for the price he's building for, have the same fixed costs he does and if you're willing to accept the same profit he's making...Presumably, he ran the numbers I mentioned based on his cost to build, his fixed costs and his desired profit, and determined that it was a good deal at that price. 

Being you asked about creativity a presume you're not looking to sell naked land.

I presume I would have to actively manage commercial deals for a full decade to get back to where I am today, in my career.