So they are about 18 months old?They're 2 yr old Barred Rocks. This is their first molt.
..and if you use supplemental lighting or not.It may go until spring. Much is dependent upon the age and breed of the birds.
Yeppers!High protein feed is good to help them grow those feathers back. Once they are ready they need at least 13.5 hours of light to tell them it's time to lay eggs again (some want more hours up to 15)