HELP! 10 month old GSP adoption questions Behaviour

I need some advice!

We adopted a 10 month old GSP/Dane mix in July and I need some advice. I have three young sons who are very energetic and was looking for a dog that would keep them busy in the backyard and give them exercise while playing with the dog. I have had Danes before, but haven't had a dog since having children 7 years ago.

This is my first time with a GSP and I knew little about the breed before adopting the dog. The previous owner gave me little information about her needs and it seemed like she had more of the Dane personality than a GSP.

She is a very smart girl and learns very quickly, but has picked up a TON of bad habits. She has dug a hole in my carpet within seconds, chewed through cords, knocked down my kids and play bitten them daily, eats off the counter, growls at men, growls at other dogs, barks constantly in her kennel and has even bent the wires and escaped it several times, and pulls on the leash STRONG!

She has been play biting the boys for a few weeks now and it seems like I am always, ALWAYS telling the boys NO and the dog NO. The kids start school next week and so I feel like I will be able to get more consistent with the dog but she has SO much energy.

She will JUMP full force over the couch and lands on a kid, and last night she half play/half protectively bit two kids who were over for a cookout with their families. That felt like the last straw for me.

She begins obedience classes tonight but has growled at all other dogs that we have seen on walks.

I took her to a dog park today to try to get her prepared to be around other dogs tonight and she was friendly with another mutt, but literally trampled him playing the whole time . Once she finally ran into the other dog and the dog rolled a time or two I knew it was time to leave the park and go home.

I have NO idea what I'm doing with this dog. I've even contacted the adoption rescue place asking if they thought I should bring her back after she bit the two kids last night. I usually live in happy oblivion to reality and just suck it up and endure hard things, but I really need some solutions with this dog or I may take her back.

Please help with any info you have for me! I just bought a puzzle toy, have 10 tennis balls that we throw for about an hour a day and am trying to get her out for off leash time in a big field of bunnies by our home.

I think that could be your problem, she is a young active dog It could be that the children are unexpectedly hyping her up even more,It is important you teach both dogs and the kids how to interact with one another, nothing like running screaming kid/s to evoke prey drive.
She is probably biting the kids due to over excitement.
Here are some tips that might help to settle her
SIT on The dog (lead)
http://sanityshome.blogspot.co.uk/2010/01/sit-on-dog-aka-long-down.html

Another one is the Place command http://www.dog-obedience-training-review.com/go-to-your-spot.html

Flirt Poles are also great for learning impulse control & focus

BITE INHIBITION:
http://www.crickethollowfarm.com/biteinhib.htm