I may be a little bit late for this topic, but I figured I would add my $0.02 anyway.
It sounds like you are doing a wonderful job crate training Missy. Just be patient, give her at least a few more weeks with the crate. I know it may seem cruel to be "putting her away" all the time, but remember, when used correctly, most dogs actually like their crates! My 1 year old Pit X Dutch loves (almost) nothing more than to lay on a comfy blanket in his crate and play with his kongs. He dosen't need the crate for housebreaking anymore, but I keep it around simply because he feels so comfortable with it. So keep doing what you're doing - take Missy out as soon as you get home, then have play time after she relieves herself outside. Keep her near you when she is out of the crate - as Saje said, you could leash her and tie the leash around your waist. That way, if she seems like she needs to go to the bathroom, you are close enough to scoop her up and bring her outside, avoiding "accidents" in the house. When she is in the crate, make sure she has a blanket and toy to keep her buzy. The most important thing is patience. Missy will catch on eventually, but don't take the crate away until you are 100% sure she is reliable enough to leave in the house alone. Better safe than sorry!
As for the nipping issue, always make sure that you have one of her toys available when you are playing with her. As soon as she starts to nip at you, show her the toy, give her the sit command (if she knows it), and as soon as she sits, give her the toy. By interupting playtime when she starts to use her mouth, you are letting her know that nipping is not an acceptable form of play. By making her sit, you are 1.] reinforcing basic obedience training, and 2.] calming her down. And by giving her the toy, you showing her what IS an acceptable form of play - her mouth on the toy, not on you. If Missy dosen't resopnd to your command, or to the toy, then do what Renee and Saje said - walk away.
As for barking durring playtime, try the same things as for the nipping - make her sit, then when she is calm start playing again. She should soon pick up on the fact that each time she barks, the fun stops. If that dosen't work, try walking away - she'll come to associate barking with you leaving, and won't want to do it.
Good luck, and let us know how it goes!