Underline blank space (e.g. forms) - IMHO, best combination of effort and results is to use the special space, which Word will underline - CTRL+SHIFT+SPACEBAR - this is much narrower than the underline character, ____ , that most people use, so it lines up a little better on the right side. (Though, this is still technically inferior, it's easier.)
Grey border after saving image - apparently related to embedded ICC colour profiles - easiest workaround, re-import image, BEFORE SAVING, cut and paste as bitmap, then save/recompress - http://www.pptfaq.com/FAQ01066_Inserted_images_have_an_unwanted_border_or_lines_on_one_or_more_sides.htm
Put two defined styles on a single line - manually add the "style separator" to the quick access bar.