HI, i too have chooks, 17, but also 2 newborns ( more to come)
Giving them bread is ok now and again, as it can get stuck in their crop. Best treat for chooks is a cauliflouer or broccoli as they love it and it gives them something to do, or if ur like me and really wanna treat them go worm and slug hunting collect them up and give the worms etc to the chooks, they r so funny!!
The fox problem.. well... i would suggest just making sure the chooks are locked up well, have wooden flooring in their hut and secured b4 dark.
OR... u could sit out at night and hit the fox over the head, it shouldnt come back then x