He should have a green card with a taxpayer identification number that you can run.
No, he won't have a green card. Check with his employer. He's a student- is he working at a university?
It is against US law to work at anywhere in the US w/o a FICA #.
He has photo ID, drivers license?
How does he work without a Social Security number? His employer is required to take out taxes from his check. I smell a rat.
I dont think he could have gotten a Michigan Drivers License without a social security number (from what Im finding online).
I don't know how he can work on a student visa. W/r/t to renting to international students, it would depend on the circumstances. When I was in law school there was a 1 year program (LLM) that a lot of international students came to the US to do. It's $64,000 and international students can't get student loans, so if they have enough cash sitting around to pay $64k for that, I wouldn't worry about the rent being affordable.