How does a foreign student file taxes?

My friend is an international F1 student in college. He's been living in the U.S. since 2015 (except for a year-long absence between September 2020 and September 2021). His parents who live abroad pay for his tuition and living expenses. My friend earned $13000 from an internship last year. Now he has some questions about his tax reporting.

 

1. Can he file taxes as an independent taxpayer given his parents are abroad and have not filed taxes in the U.S.?
2. Considering his time in the U.S., should he file his taxes as a resident or a nonresident, i.e. using form 1040 or 1040 NR?
3. He does not receive a 1098-T form. Can he qualify for American opportunity credit?
4. Besides the $13,000 W2 income which is his only income, are there other items he needs to include in his tax return, such as education expenses?

 

I'll appreciate if anyone can give me answers.