Yeah there are. At the high end I think Jane Street will train you in OCaml when you're a junior new hire, assuming you show the competence and care to figure it out. I imagine you have to show some functional programming experience (using it, not work experience), knowledge, or even aspirations, but I've often heard of the actual practical experience coming from the job.

Yes, there are banks using Haskell for many important processes.

You can, and I know a few people who work with it, but from what ive heard theres very few positions out there so you hace to be very good as opposed to just an average Haskeller.