Partial restore to new server

Hi, I am moving to a new server after an experiment of Both are manual installations and I would like to import only channels, messages in channels and direct messages.
I’ve done a mongodump of my source server and see a whole bunch of files, I think that if I only keep the files I want and pass them to mongorestore, it should be possible to import what matters to me (nearly everything except administration settings). Is it possible ? If yes, what are the files I should keep (or remove) to discard admin settings. Users are synchronized from an ldap server, are ids consistent if I skip them in the import process or should I keep them in the restore ?
Versions are not the same between source (3.2.2) and destination (3.9.0) is it a problem ?