I guess the simplest and cleanest would be to sell and pay the tax in the foreign entity and then use the local LLC going forward.

Partner with another flipper or someone who has a realtor on the team that you could utilize.There are other ways but these to me are the simplest.

In the simplest case of an investor with a single primary residence and a single rental property, where one of the properties is owned free and clear, and the other is mortgaged, in terms of tax benefits, does it matter which property is mortgaged?  

In its simplest form you plan on executing a lease option with a friend.

The simplest way could be that you get a conventional loan with 20% down and have the seller finance a portion of the down payment.

@Dave Holman Using the simplest math and if this is a single asset LLC: $100k asset, $50k liability, $50k value. 10% interest should cost $5k... and new partner would be sharing 10% profit/loss.

I"d say the 7-8 cap is a real possibility here if you are good at interpreting balance sheets and income statements to see the potential in a property rather than looking at what the numbers are in their simplest form.  

My friend has about 10k in capital and is very willing to manage and improve on a property but has no idea how to obtain a mortgage or put together even the simplest of deals.

Not to be dodgy with your question or anything, but the simplest answer to the baseline expectation would be when ROE has dropped to the point that you believe you can achieve a higher return at the same or lower risk level in another investment opportunity.

My exit plan (boiled down to its simplest form) when I started was buying single family homes to rent that I could price 20% below market value and sell quickly.