As for me talking to a seller on the phone, I haven't build up enough momentum yet for that hehe!

Build up you list of other investors and credibility at the same time.  

What is the best tool to passively invest and build up the nest egg while I am out of the country?

I'd like to go big or go home and jump right in with commercial property (apartment complex, etc) but without having "Big" knowledge, I've decided to go in small until I build up some best practices and equity/experience and then work my way up the right way.  

I also want to build up a portfolio of rental properties.

The next build up I think is going to be behind the MotorCity Casino. 

It should give a chance to build up some capital and learn real estate at the same time. 

This gives an ROI 4800/16700*100 of 29% before counting equity buildup; tax breaks and potential appreciation.  

Plus with the amortization dragged out, you are not going to build up much equity in the property.Of course it is possible that some people are simply buying with cash, but without using the leverage of a mortgage, the return on real estate is much lower.

In short though if you can find good deals and put in the work to build up a list of cash buyers (ideally though sometimes non-cash works too) you should be able to make it work.