3.2 I have found a position in another department, and the supervisor seems to be ready to accept me. Will there be a selection board?

Not necessarily: it is left to the department in which the position has been opened to decide. It may depend on whether a vacancy notice has been published or not, whether there are other internal candidates, or whether the departmental management wishes to have the opinion of a board. There will in any case be discussions with the Supervisor, Section Leader, Group Leader and your HR Adviser.