Hey sathi, 
Regarding these matter, one of my fren has been into this condition.
Using SSN at work , doen't really matter as long as you have good status
But immigration at Chicago, JFK are kind of very strict for the student, there are some student nepalese who has been deported and i know them. Their case was because they have sold alcohol to minor and when the immigration officer check his name and DOB they found that he has been to court because he sold alcohol to minor while working in the gas station. 

Normally, immigration do not check each and every student. but sometime, they ramdomlly do check Esp, at Chicago and JFK. 

As long as you have not been in any criminal case . you should be good. They can't say anything  for just using SSN for your work. There are also some way how student can get part time job off campus job. Rather you can say you are doing CPT through college. 

So don't worry. have a nice trip to nepal

Cheers