Leslie,
What you are experiencing is not uncommon with such a young dog, she just needs to learn how we as humans play (as puppies that is how they play, rough and full of energy). You are doing the right thing with Obedience classes and should start as early as possible especially with early socialsation (there is a thread at
http://www.rottweiler.net/forums/sho...&threadid=5170 that you may find helpful).
As too how to stop her from biting and growling simply either have her outside or somewhere set up that you can leave her. Bend or sit down and start playing with her (you can use a tug toy if you like) and as soon as her play gets out of hand (for me that is biting me directly) simply mark the behavior (the words ARRT or NO are the most common ones, it helps the dog to make an association between the behavior (biting) and what follows) stand up and walk away from her leaving her on her own. Wait a couple of minutes and repeat. She will soon learn that when she bites you walk away and leave her on her own. When the sole objective of her behavior is too play and interact with you she will quickly offer something else. Keep playing with her until she bites you and she will get the idea if she plays nice she will get to continue to play with you. Be consistant in your training and you will see results.
One possible problem people experience from this is the as they walk away the dog latches onto the their pant leg to try to motivate a continuance of the game. If this happens simply bend down (without looking at her if possible) remove her from your leg and move on. No fuss or fan fair. She will soon get the idea that this achives the same result.
Hope that this helps,
Mick.