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

I Have A 7 Year Old Cockapoo With Aggression Issues. I Have Tries Everything .?

Behaviorists, medications, training etc. We adopted him 3 years
ago. Essentially, he bites under ciertain circumstances: If we try to
take away something he has that does not belong to him, he’ll growl and bite. He will do this when he is resting and doesn’t want to be bothered. We have learned to manage the situation in that we know the circumstances where he will bite and we avoid these situations.
We tried prosac which turned out to be a disaster, he became more aggressive, we’ve gone through the whole training/behavior modification stuff which has helped but there does not seem to be a way to keep him from biting permanently. The vet/behaviorists tell us it is genetic and we just have to manage the sitiuation. Is there anyone out there who has tried something different? He is a great dog 95% of the time but his aggression limits us from allowing him to interact freely with other people. My husband is apprehensive around him and all in all, the situation is not ideal. HELP!