Before you do anything, get yourself a free utility in here in freestuff called objaction scaler. It helps with the export and import into 3ds. If you don't use the scaler 3ds sometimes moves your obj centres, making the re-imported obj act strangely sometimes. The scale between 3ds and poser is roughly 1/100, but there is not 100% agreement on this, but it's close enough to work with.