Make sure you protect those new trees from the chickens until they are well established.
They can destroy the plant and dig at the roots enough to kill the plant.
Not as long as it empties overnight.
Have had a couple that never fully empty, even after treating for impacted/sour crop...
....not much to do about it.
I don't free range either....but here's what I've surmised from reading here over the years.
Are they going back to the coop in their own at dusk?
Good to start them free ranging for the first time late in the day,
30-60 minutes before they normally go to roost.
They won't go too far at first...
Eh...not sure.
http://www.jupefeeds-sa.com/documents/GraniteGrit.pdf.
I bought about a 2 gallon bag of granite grit from the local mill, they put it in their chicken scratch. Ran it thru a colander with 1/16" holes. Bagged the smaller stuff for the chicks and sprinkle some over a chunk of sod...
The low existing bird is usually the one most aggrieved with newcomers.
Not sure if they are protecting their place,
or just glad to finally have someone lower to beat on. :gig