"If we rent it for two years, live in it for two years then rent it for three years then sell, the Full $550k is excludable and tax is due on all depreciation?"
No. Because you moved into it after it was rented, those first two years are "non-qualified use". That means you could only exclude 5/7ths of the pre-depreciation gain (7 years of total ownership).
@Carl The 2008 thing definitely applies. It applies to periods AFTER 2008 that it was not their Main Home, so that means it would apply to renting in 2015.
