Past, present or future. Or all three... the choice is yours.

It depends on what you are writing. Most newspaper stories are in passive past tense.

I think your teacher said that because the past tense is the most frequently used tense for writing stories. Clearly, you can write in whichever tense you want. The challenge is how will the reader react. We tend to prefer hearing stories about what has occurred as opposed to what is unfolding as we speak, especially if it is anything longer than a short story. If you wish to be provocative or intriguing, a tense other than past is fine. You might want to take a look at the following: http://www.novel-writing-help.com/past-tense.html

It depends on the story. If you are writing about things right now, it would be present tense. If it is something that has previously happened, it would be in past tense.

It all depends when the action takes place. LOL.