The other watchout is if you lose your job you are required to pay the money back quickly, like 30-90 days with most 401K's or the loan gets converted to a withdrawal that comes with tax implications and penalties. 

Work with a lot of expats and foreign nationals in this space tax related.

The fact that you have a TAX-FREE income is crazy good.  

Yes, do the tax exchange if you can.  

The single biggest advantage of selling your homestead is that you can take all the Cap gain tax free if you have lived in the home as your homestead for 2 of the last 5 years. 

The sum total of taxes of each of the 4 units will usually be higher than if it were apartments.

Prioritize quality locations.Keep healthy amount of reserves per property, hire a PM, and hire a tax friendly CPA(not planning just prep). 

I have been listening to the podcasts for years and have finally gotten serious about making this move to better my families situation. 

The seller may not want to do this, as many of these guys are benefiting from the tax deferral which comes with NOT moving title over.

On your tax return you would report the proceeds, subtract costs and proceeds paid to seller, then the remaining profit would be your flat fee.