As far as creation goes I would keep objects at the centre (default in most apps I thought). You can see the grid axis and tools like mirroring and multi-replicate around an axis will be easier to set up. The import app may place the object at 0,0,0, or centre of screen or......... all will be different
For me the metasequoia/Terragen coords match perfectly. I can export exactly where I want It imported to