visa detail

On the application form, is the Local ID/Citizenship number, the social security number required if you live in the United States? Also, can a student apply for a 1-2 year multiple entry type if she is going to study in China for 30 days in May 2015, but may go again to study within 2 years? Does she need to include a letter from the school where she is going to study in China -- or from the Travel Abroad department from her university in the U.S.?