Appropriate responses and attitudes for IB interviews

I'm preparing for full-time interviews in IB.

The first question is: what attitude do people usually have with interviewers? I don't want to come across as too friendly, eager, humble, cocky, etc. How formal should I keep it? Would it be inappropriate to use words like hustle, grind, or are you expected to keep it very formal?

Second: I'm coming from a non-target school. I'm anticipating questions about my work ethic or education. I'm a non-traditional person for an analyst role. Late 20's, did poorly in my first attempt at college, worked odd jobs in between, now very successful in a state school (3.9+ since re-enrolling). I work full-time to pay for school. EnrolIed in community college, then transferred to a state school. I didn't really have the opportunity to go to an Ivy (prior bad college performance, too expensive). I also challenged myself with extremely heavy and difficult class schedules. How much of this story is appropriate to summarize? Will it hurt me to reveal I did poorly in college the first try or help to establish a solid narrative that sets me apart?  How would you answer questions like "What are qualities would make you a good banker" or "Why you vs. an Ivy grad" if you were in my shoes.