Your younger birds probably need to have all flock or chick feed for a few more weeks until they are laying. Layer has 4 times the calcium that chick feed has, and it can damage kidneys in birds not laying.
The orange is intestinal lining. It cannbe normal occasionally, but if see often, along with those droppings, it may be from possible coccidiosis or worms. What dosage of Corid did you give the chickens? Valbazen dosage is 1/2 ml for a 4-6 pound hen, and the dose should be repeated once after 10 days.