Yes, at 10 weeks she is too young to get pregnant. She'd have to go through heat first, and that usually happens around 6 months. And if you get her spayed before her first heat cycle it will greatly reduce her chance of cancer in the future.

To keep her from escaping/digging I'd only put her out loose in the backyard when you can watch her. In fact with a 10 week old puppy I'd never leave them out unsupervised. And if you're out there with her you can make sure to correct her if she does start to dig. Bored dogs dig, entertained dogs do not.