I'm not sure how much I can help, but I would like to welcome you to YT!
If she comes inside and pees and poops immediately, then I'd bring her in, put a harness/leash on her and take her immediately back out side. In fact, I'd use a harness/leash to walk her to her "potty area" in the yard and let her sniff around for 5 - 10 minutes. If she doesn't do her business take her back inside and repeat the process frequently and especially after she wakes up from a nap and after she eats. I would ONLY let her have playtime outside AFTER she does her business.
As far as the biting goes, unless you feel like one of them is going to get hurt, I'd let them work out their own problems. It has been my experience that males and females don't generally have real knock down drag out fights. She may be just palying or she may be trying to be dominate. If she hasn't been spayed yet, then it probably time to make the appointment and take her in. Raging hormones in a young bitch can turn them into....well a real first class bitch
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Good luck and keep us posted with your progress -- hopefully you will get a lot of responses and will find one that makes sense to you.