Should I Keep This Dog? She Has So Many Issues!?

We rescued a dog over 3 weeks ago from a shelter. Not much was known about her. Shes 3, probably a cockapoo and was either a stray or neglected but probably did live inside at one point (only had one accident and has held it for 10 hours before!). She doesn’t shed (YAY!!!) she’s incredibly loving (to me and my husband), cute and has funny quircks.. but she also has some “baggage” and behavior issues.
1. She’s very protective over her toys,treats, and sometimes her space – has bitten kids lightly.. my 6 year old doesn’t like her that much and is afraid of her.. he’s dramatic but still..I want him to like the dog!
2. She doesn’t come when you call.. she hears you, see’s you, but she chooses not to come. She’s not a big pleaser. More like a cat.
3. She just started humping our pillows AND humped me yesterday! I flipped! She was spayed 3 weeks ago!! It totally grosses me out! Guess she wants to be top dog. No no!
4. Not the easiest to train. Got past “sit” but sometimes she doesn’t

Why Does Our Puppy Do This?

we have a 15 week of cockapoo who is nearly housebroken. He is completely fine sleeping alone at night (he sleeps downstairs) and he’s totally fine when we go to work in the morning. We have a dog walker that comes to let him out and walk him in the middle of the day. When we get home, we take the little guy out, we play with him (we don’t make a big deal out of our arrival). But if we go upstairs to change our clothes or go into the kitchen to grab a glass of water, whining starts as if somebody is trying to kill him!! It’s as if we are home, we can’t ever not be right next to him. We take him for a walk at night (at least 30 minutes), we play fetch, we give him affection, we train so I don’t think he is suffering from separation anxiety. When he’s left alone, he doesnt destory the house, he doesnt make accidents (if he has to go, he goes on the pee pad), i just don’t know why he whines so much when we are home with him but not in his sight. Help!

Why Do My Dogs Do This?

I have a black lab who is 2 years old and a cockapoo that is 1 and 1/2 years old. Everytime we leave them out of there cages in the kitchen the lab will jump up and get mail or anything off the counter and chew it up. The cockapoo isn’t as bad but will tear up the stuff once it it down on the ground. The reason why I don’t understand this is because both dogs are trained and it only happens when noone is home. Why do they do this? They know its wrong.