"Prevents the Rectangle selection tool from selecting elements that are occluded behind other elements in Hidden Line Removal, Constant, Shaded, Textured, and Textured Decal viewing modes. This option is ignored if Override Object Properties is off in the Display type menu of a viewport." The preferences should save…
On the bottom section of the merge window that will appear when you run the command, you have to click those extra 'merge' buttons to tell XSI to also merge UV coordinates/materials and/or any shape animations/weights you might have on the models being merged. As for the image in the UV editor, you can go up to the Clips…