Correct. A warrant is applied for only when judicial proceedings are sought and charges are to be made.
the request to surveil the server was probably just to cover their asses for the warrantless wiretapping once it was clear that Trump might actually win. When he did win, they immediately jumped on the Trump-Russia collusion narrative because they knew it was only a matter of time before Trump figured out that they were spying on him. They were trying to get ahead of the scandal.