Typically I load in the character then the cloting separately then delete the mesh covered by the clothing. The weightmapping seems to work fine when Ive tested it but I typically dont use them.
You can also create your own weight maps if you want.
Im not sure what you mean by translation data. What ive typically done is load a bvh file into poser, save the pose and then load it into LW using PLK. In LW I use iKBoost to edit the mocap.