All you need is your passport and the ticket. 

 To leave the States:
- your Passport
- I-94 card (the little white card that was stitched to your passport at the port of entry). this card will be usually taken by the airlines staff or security officer at the port of exit and you'll get a new I-94 card at the port of entry when you come back
- your boarding pass

To enter back:
- passport with unexpired visa
- all I-20 forms till date (if you are leaving States after more than a year-long-stay here, you need to go to the advisor at your school and have it endorsed before you leave for Nepal - usually takes about a week)
- boarding pass

That's all you need. But if you have one, carrying your school's ID won't hurt.

To leave you need 

1. Your Passport
2. Your Id.
3. Your initiary.  that's all

To return back to US. It depends on which way u coming.
But for all- Its ur valid visa, Id, I-20 and a letter from your advisor from school. And while you reach to US immigration they will check you by asking your address. If its not the same as in the record and as you say, it may be a problem. they may waste your time ..