Her name is Mandy Line, but she's not made it into the credits yet. Outgoing Costume Designer, David Zyla, is still credited. Perhaps Mandy shows up in the credits next week in time for the 13K episode?
Yes, Renfroe is a FOJ that stuck around Y&R and has proven himself with both the cast and crew there (I've heard he's very beloved). His work is very artistic/cinematic, and like I said, you can always tell when either he or Sally McDonald are directing. His work on GH was also quite stellar as he did a lot of key episodes during Guza's various sweeps stunts storylines.