Yes, I often underline short stories. Underlining helps me to mark important passages, interesting dialogues or beautiful descriptions. It makes it easier for me to review and remember the key points later.
It depends. Usually, you don't have to underline short stories. But if it's for a specific style guide or assignment instructions that say so, then yes.
It depends. Usually, italicizing is more common for titles of short stories. But in some cases, underlining can also be used, especially in handwritten work.
It depends. Usually, you quote short stories when referring to specific passages or quotes within the story. Underlining is less common in this context.
Most of the time, short stories are italicized. It's a standard practice that helps distinguish the title from the main text. But there can be exceptions based on the requirements of a particular publication or writing guideline.