Super nice purple fairy chan for me - and yeah, you can use the fairy as a manyu
But I'm not sure exactly how much xp she gives your girls, but it's A LOT. My Yomena can lvl from 40 - 70 no problem, so xp fairy gives is probably even higher than that, OMGz love it. Maybe Jap Wiki has exact parameters.
And really nice Christmas event, I realllllly want 5 star Chloranthus, but if I can manage a 6 star pull no complaints here lol. So is this batch of Christmas girls the only one, or would they make more? Seeing as there's still like a month 'till 12/25..?