Even IF you load an imported OBJ file the texture is going to be missing until you assign the material / texture in the Poser Material Editor.

Doesn't matter if it's 3DS or OBJ in either case. (as far as I've know from my own experience)

Next best thing to do is once you've done whatever you need to do with the imported model in whatever format it is after having been brought into Poser and assigned it's materials/textures in the Material Editor is to save it to the Poser Library as for example a Prop.

If it's a 3ds file, in this case, save it out from Poser as an OBJ then import it again into Poser, assign your material and save it to the library.

I don't believe there's any way around avoiding the Material Editor in a nutshell.