The Basic Rules Are Simple:
Graduating seniors or super-seniors can apply for the fellowship. You have to be done with your degree(s) before the June of your departure.
Applications are due thee September before your graduation. If you are walking in June, but aren't actually graduating until the next December or January (because of student teaching obligations, or because you are finishing up a requirement or two), then you submit your materials in September before your actual graduation, not the September before you walked in the ceremony.
International students can apply, and so can students who will be off-campus in the fall.
The applicant must spend a year outside his country pursuing his project.
The applicant cannot return home any time during that year, and can’t spend time in countries where he had previous spent a significant amount of time (around 6 weeks).
The applicant cannot go to countries for which there are travel warnings or to countries under U.S. Treasury Department embargo. To see which countries are on those lists, go to:
http://travel.state.gov/travel/cis_pa_tw/cis_pa_tw_1168.html