I would say RUN, not walk away from this potential tenant. A few red flags in the small amount of detail:
#1 - showing up in a car with "all his stuff" - I know that people hit the skids and things get away from them, but someone wanting to make an impression would have handled this a little differently.
#2 - leading with not paying rent - he's admitted he's skipped out on rent up front. Again, everyone has a story (and I've done the same a few times), but that's not something I'd open up with a potential landlord as my initial introduction.
#3 - expecting to move in right away - having unrealistic expectations about how things work. This isn't like putting a man on the moon, this is a fundamental skill. Maybe he just arrived from Mars and has absolutely no idea how things work here on Earth. But ... he does know rent is due and he didn't pay.
#4 - As far as asking about the employer questions, I'd just verify that he's employed for starters. Not sure what relevance being an engineering major is. It's not a proxy for intelligence. All you know is that he has said he's gone to school.
Could go on, but I recommend staying far away from this prospect and seeing who else pops up. Put him on a waiting list and contact in a few days if you really are feeling charitable.