It's just the Circle of Life... they need to live, so they need food.
Yes many birds in the wild life eat each other
Hawks, falcons, magpies, owls, chuck-wills-widow (occasionally)...mostly the larger birds such hawks, falcons and owls (aka raptors).
They will eat young birds, yes.
Any of the Raptor type birds will and do. Eagle, hawk, I suppose the carrion eaters would if given the chance.