Just my opinion but I don't FEED chicks anything but grower till they're well over 10 weeks of age because the nutrition is optimized for growing poultry. I let them forage when they feel like it so they do get greens, bugs and seeds but to feed things other than the grower you have to consider primarily how that might be reducing the protein content. It might not hurt if you are feeding a high protein game bird grower.
i was just thinking of throwing them a couple leaves of lettuce from the garden once in a while as a treat, but, yes, keeping them on the chick starter/grower till 10 weeks.
Yes, you can feed them now. Chop it fine for the first few days then you can cut it progressively coarser until they are able to tear off pieces themselves. Just don't give them a lot at once. No more than what they can clean up in about ten minutes or so.
