FHA does have some guidelines to purchasing due to job relocation or 100 miles away from your existing primary.Do you currently have any mortgages appear on your credit? 

If I know I want to walk 1,000 miles by the end of the year, I can come up with a plan of how many to walk each day, week, month, quarter, etc. 

You're looking miles deep, but you haven't even gone 1 step on mile 1 5280 steps in.

When he gets plastered, see if he will sign off on your situation.Joking, though only half so.

I have about 140k in cash available, and looking for guidance on the best route for funding the second half of constructing a duplex.

The reason being is they can quote you a low rate (too good to be true usually) and then half way through the process or even worst at closing the rate is subject to what it is that day and then they excuse themselves because the borrower never asked for a rate lock or were never aware of what a rate lock is.If you have any more questions I am happy to help.

Also, if I place bad tenants frequently, I can count on being fired, so what sense does that make to ruin my reputation and lose other business for half or 1 months rent commission?

Downside here is you have to pay your 401k back and are limited to the lesser of 50k or half the market value of your 401k.In either of these scenarios, I think you need to evaluate the details as a whole with numbers. 

If I were you (and there are many things I don’t know about you) I might put half into cash flowing real estate at 60-70% leverage (to get depreciation, loan pay down, cashflow, and hopefully appreciation) and invest a large portion of the rest into something else.

In order to qualify for real estate professional status, you need to spend more than half of your work-related hours dealing in real estate directly, or more than 750 hours during the tax year.