I really think Varlamov is the ideal target among the FA likely to be available. Freddie will likely be more expensive and his availability has been much more of a concern than Varlamov lately. Raanta is better suited as a backup at this point so keeping him would pretty much be slotting Koochie in as #1. There are not really too many great FA options in net this year for a 1a/1b, more backups.
I don't think he will never lack in confidence, lol, he seems possibly overconfident at times. He does need to settle down a bit more which should come in time as he logs more NHL minutes, also glove could use some work. But yeah he has all the tools to be one of the best goalies in the league right up there with other Russians like Igor, Ilya, Vasi.