I would imagine that it is a problem with the exporter, or maybe a
convert angles box has not been ticked (I've never used pandasoft exporter so I'm just guessing). But, to remedy this you could just use
dbRotateObject( ObjectNum, 0.0f, 90.0f, 0.0); or
dbRotateObject( ObjectNum, 0.0f, -90.0f, 0.0); depending on which way around you need to rotate (right or left). There is also a function which will lock this rotation
dbFixObjectPivot( ObjectNum );, which will make your model behave as though it's new angle is the default orientation.
As for the BSP, stay clear! The only advantage of using BSP is the fact that it has collisions and portal occlusion built-in so to speak, but it is an old format and implementing portal occlusion yourself is not that difficult. Just stick with the DirectX format(.X), and use a physics or raycasting system to perform collision detection.
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