Finally, a topic I can actually offer some information on rather than always asking others for help! I have had anywhere from 10-25 free range chickens on my property for the last 3 years and have had grapes and/or figs (& fruit trees) for most all of that time. Make no mistake, the chickens hunt for, catch, and eat bugs from daylight to dark every single day. In fact, I feed them very little in the summer and they do great. You can be sure, though, that they equally love grapes and low hanging figs so you certainly have to fence around such things. I only have one row of grapes and its about 30 feet long so I just put woven wire around the whole row and barely drive the T-posts in the ground so I can take fence down very easy after grapes are gone. I do same around my figs. I make little round fence sections around each fig and let it free stand except for one t-post per fig which I attach the fence to in order to keep it from blowing/falling down. I haven't done this for peach trees and have accepted the loss of peaches that are 2.5 feet or lower, which isn't many for my trees. You may be happy to know that my chickens have never once flown into a tree to eat...if they can't reach it from the ground it is safe.
As I said, the chickens eat tons of bugs all day long. HOWEVER, in my opinion they don't benefit the grapes or the figs or trees by the consumption of bugs for the same reason they don't harm higher fruit.....they only eat bugs on the ground. SInce grasshoppers and other ground bugs aren't a big problem for my fruit trees, this isn't much help. Even CM's and OFM's apparently stay high for the most part. I know that part of the cycle of several fruit tree pests include falling to the ground and developing, but for whatever reason, in my experience, those fruit tree pests seem to do well in spite of the chickens-maybe because they quickly burry themselves. My chickens don't seem to be more active or to prefer hunting under fruit trees either, so this also suggests to me that they don't get a lot of fruit tree pests. ANd believe me....I have them! OFM and CM are heavy on my place.
Now, one last thing you mentioned is a HUGE problem for me- hawks. Also owls. They kill my chickens on a regular basis- much worse in winter than summer but definitely year round. I just consider it a cost of free ranging and periodically let my chickens hatch 10-12 new chicks and I keep them penned up until they are almost grown. Hawks will kill 12 baby chicks in 2 days where I live. But they only take an adult about once a week. That's often enough to be infuriating, but not much can be done. To the likely horror of some people here and elsewhere, I confess to having "disposed of" several hawks but there are always more and I've never been able to tell I've helped so I no longer bother. Well, that's way more than you probably wanted to know but I was excited to be able to offer someone a little information rather than beg for it myself. If you have other questions let me know.

Dark Cornish are good mothers and good free range chickens. They are likely as close to wild as you can get. For snakes, mice and rat hunters barred rocks are hard to beat. My light chickens such as leghorns and banties the hawks and owls hunt. My barred rock would call each other with an "errrr" noise when they saw a shadow hit the ground of an overhead bird and they all ran to get under something. Barred rocks have a predatory hook like beak. They are all great bug hunters. I'm not keeping chickens now because they tend to dig holes and be a lot of work. The 30+ years I kept them they all had their benefits. White chickens attract predators here as well because they can be seen far off. I had a dark Cornish disappear once for a month or so I thought coyotes got her. 4 weeks later she showed up with 23 chicks . I followed her home that night crawling all the way. She raised those chicks under a mulberry tree. I was 8-9 years old at the time and never forgot that breed because chicks hatch in 21 days and for 4 weeks she stayed on that nest or close by eating grasshoppers and mulberries. She then raised those new chicks on the same diet until they could travel and come to the pen for corn. I'm no chicken expert but as mentioned they don't eat fruit out of the tree unless it's within jumping distance of the ground. Guinea are loud but even better bug killers and lower maintenance. I kept some in with my chickens as alarm birds to let me know when a predator was attacking.

Thanks. What are OFM and CM? All my grapes are on a high wire and should be fine. Do the chickens keep weeds down also? I plan on butchering prior to winter here. That will minimize the hawk issues!!

OFM = Oriental Fruit Moth
CM = Coddling Moth

OFM is Oriental Fruit Moth and CM is codling moth. Both are MAJOR problems on my peach trees (and are perhaps the most common peach pests for most areas). They are in the form of tiny white maggot-looking "worms" when they enter the peaches and burrow to the seed, but at some point in their life stage they are moths. You might expect chickens to eat them at the moth stage or some other stage since part of their life cycle involves being on/under the ground. But as I said, I've had them in great abundance in spite of my chickens and never noticed the chickens taking any special interest under my fruit trees so I don't think they get many of them if any.
Chickens do eat some grass/weeds. I see them do it a lot and also find grass/weeds in their stomachs when I butcher them. (apologies to the squeamish!) However, mine seem to prefer yard grass above all weeds so I can't say they really help with weeds. Now, I also have some ducks and geese, and they are MUCH more help with weeds. In fact, I've heard people swear that geese are incredible at keeping strawberries free of weeds because they don't eat the berry plant but do eat the weeds/grass around and within them. All this being said, even though my ducks and geese eat an amazing amount of grass and weeds, I still can't tell you they are a huge help simply because they seem to just eat anything green and tender and are not any more attracted to rogue weeds than grass in my yard. Now, if you fenced geese into a small area, say around a fruit tree or grape vines, I think they probably would be very helpful at eating all the weeds within that parameter. But mine have almost 8 acres to roam freely so their consumption of weeds is too spread out and random to make much difference.
As for hawks and owls, butchering your chickens before winter would help and I do that to a degree, but I keep a few around. I also agree 110 % with ClarkinKS that white chickens get hit much harder than others by predators.
Hope this helps. Also, my chickens do roost in one of my barns and create huge piles of chicken manure which I compost along with with wood chips and leaf litter that I get from local power company when they trim trees. I use it on my garden but folks here tell me it may cause too much vigor in my trees, among other problems, so I'm not sure if I should apply it to my fruit trees or not???
Anyway, free range chickens are fun, the eggs are incredible, the manure is great, but I can't tell you that they really benefit my grapes or fruit trees in terms of killing fruit tree-related bugs or eating weeds in areas I need them controlled. But good luck!.

My ladies are always digging around the trees, pulling out the mulch. This spring I am solving this issue by cutting out all grass and mulching the entire orchard. Either way, the hens rock and rarely try to fly over the fence. My trees are small and only carry small amounts of fruit so I didn't notice them going after any fruit.

Here is a picture with the coop.

I had about 20 chickens I allowed out in my orchard to see how they would do. They did eat the bugs and scattered the mulch. They also ate all the fruit and leaf buds they could reach and from that point on no chickens allowed in the orchard.