My brooder raised chicks normally don’t start to roost until 10 to 12 weeks of age. Until then, they sleep together on the floor, usually in a corner. I have had 5 weeks olds roost and I’ve had some take a lot longer to start, but 10 to 12 weeks seems to be my average. I let mine roost when they decide to roost. If you have decorative chickens that can’t see or fly then things can be different.
Do they need to roost? No, not really. It won’t hurt them to stay on the floor. It may be a little harder to manage the poop if they are on the floor, you can put a droppings board under a roost to remove a lot of the droppings so poop management can be easier, but as long as you keep the poop from building up in their sleep area, it won’t hurt them.
They poop a lot at night. The reason you don’t want them sleeping certain places is you don’t want the poop there. That might be net boxes or places it is hard to clean the poop. Poop management is the only real issue. In spite of all you hear about how their feet get hurt if the roost on something flat or if they don’t roost on something flat (yes you hear arguments for both) they do fine either way.
Personally I like the nest boxes open before they start to lay. If I have a problem with the nests, maybe the lip is too low so they scratch out the bedding or they sleep in the nests, I want to correct that problem before they start to lay, not afterwards.
As long as the feathers are not actively growing it does not hurt to cut the feathers. If the vein of the feather is red it has blood in it and it is growing.