Did Eri rewind Deku's arms?
no, the little girls power healed him during the raid.... It's possible it was due to the effect of his dream, though if you look closely when Deku is battling Overhaul with Eri's help his scars disappear after he defeats him.
Does Eri like Deku?
During her rescue, Izuku is the first person not to call her Quirk a curse but rather kind and gentle, driving Eri to tears of joy. Since the rescue, Izuku's earnest and genuine desire to see her happy again made her grow fond of Izuku, seeing him as an older-brother figure.