1. Talk to your vet about the issues you are having with her, he/she may have some suggestions for you. Tell them what diet you are feeding your dog to make sure she isn't missing any nutrients (sometimes dog will eat feces if they are missing certain nutrients).
2. Work on teaching your dog NILIF (nothing in life is free) or Top Dog training.
The excessive eating and always seeming she is hungry is a classic Lab trait, they have endless stomachs and will eat & eat & eat if you let them. Even if they aren't actually hungry they "think" they are. DO NOT GIVE IN TO THIS BEHAVIOR! In fact I would start teaching her that if she wants to eat she has to do something for you
EX: you must sit on your spot while I am preparing your food
don't even think of nudging the food bowl/my hand while I put it down
sit there and do not even think of eating it until I tell you 'ok you can eat'
nothing in life is free buddy and you will sit still for ME before I feed YOU.
Teach her that she can only eat if you (other family members) tell her she can.
I recommend Bitter apple spraying the trash cans, one lick of that stuff and she won't go back. If you see her counter surfing tell her 'OFF' or 'Leave it'.
3. Crate train IMO this is a MUST for owning a dog. All new members of the pack must be crated until they EARN the trust to get free run of my house (in my house it's age 3). Free run of a house is dangerous for a dog as you have learned with your sons things being destroyed, be thankful your dog wasn't hurt.
-How to crate train and older dog:
Start out by crating her for short periods of time while you are home
DO NOT let her out if she whines/cries because that teaches her that if she whines/cries long enough she will get out.
Tell her to be quiet and as soon as she is quiet let her out and give a reward (a piece of dog food)
Increase the time longer and longer while you are home (gradually over a month)
Eventually you should be able to leave her in the crate at home alone.
Feeding her only if she is in her crate.
I know this seems like a huge commitment, but the end result is well worth it.
I know you can do it and I know that she is more than capable of becoming the dog you want her to be. Training has more to do with training the human how to properly respond to their dogs behaviors by remaining in control of the situation than it does training the actual dog. Dogs need consistency (from all members of the household) and they'll do whatever you want them to.
It sounds like she has something she loves (FOOD) that you can train her with, you are fortunate to know her "love" use this in her crate training and also with her manners and you will once again have a dog that you will love to be around.
-Work on becoming the top dog in the house/nothing in life is free
-Work on crate training her