re: Dress/attire for interview in different department of your company?

I would apply the general standard. Dress in the nicest attire that you would have to wear on any given day in the new role.

If they’re interviewing others from outside the company who turn up wearing suits while you have business casual on, then you’ll be running the risk of being perceived as having been overconfident that you’re the front runner.

Always a suit if it is in the office. I’ve had interviews at either breakfast or lunch before at a restaurant and just wore what I went to work in which is business casual. Maybe a sports coat depending on the company/position. Since you said school I might not wear a tie.

Depends on what you would be wearing to work every day. When interviewing for any job (internal or external) I always dress one level up from what I would wear on a daily basis.

Know your audience.

In my profession, suits would be too formal/off-putting for the “hip tech vibe”. Yet if you wore slacks, a collar shirt, and a sports coat, that would be viewed quite favorably.

All about your audience

I assume you know the interviewer in some way. Do they wear a suit or are they business casual?

Dress like your new manager

You can still wear your orange apron, just wear a nicer T shirt under it.