We can't really advise but... of course under normal circumstances - as the source and target databases have to be on the same mySQL server - the host, user names and password are most usually the same as the ones you use for WordPress. Only the db Name would be different.

The Invision script was written by a user who successfully imported their own db. I do not know if t has ever been used by anyone else - Invision is not one of the more popular systems after all.

As it says in the help panel and the first page set of options - only users,  forums, topics and posts are imported. We can not import attachments. If you want to go that far then the conversion people that Ike mentioned above would be the best way forward.