IIRC I found I had to add the textures AND the associated models for them to work correctly. I didn't use an importer, just drag and drop while being mindful if you're overwriting something already there, especially the models folder. I never dealt with directx errors, did you install hook 5? I do remember it all started working on about my third attempt. Also I open the game straight out of the binaries folder. And also check your options on the left of the main menu that it's set to directx?
Hope my rambling helps out. I find it all kinda like working with legos which I used to hate as a kid. I grew up preferring getting my GI Joe right out of the package but now that I'm older I can have fun with legos too. Speaking of GI Joe, Baroness would make for a fine model...
