We have quite a few chickens and we confine them at certain times of the year and let them range other times. As for the gardens, flower or veggie, they will really damage young plants and as indicated will also damage certain fruit.
They also scratch up soil and mulch looking for food and to take dust baths. My wife gets furious when her fancy gardens are all messed up due to this. On the flip side, once your gardens are very well established they seem to be OK and not to damage the plants. They eat TONS of bugs and pests and it is cute to see them running around on the 'range.'
Our chickens tend to free range in reasonable proximity to the coop, say within a 2 acre circle. Certainly if you have foxes and (even worse) domestic dogs running loose you will lose some. Also as said, lock up the coop at night to keep varmints like coons out. Skunks are interesting, they'll steal eggs and kill and eat mice but I have never lost a chicken to one. We even let one live in the coop this summer to get the mice under control.
After many years, we built a coop with a large enclosure so we have the option of managing the birds whatever way we want.
I have posted some of these pics before but we really like the aviary and coop and I think the birds do too!