Thanks for all of your comments, advice and encouragement from my post on Parenting. It was fun to read what you had to say. And, just in case you were wondering what I actually did in each of those situations, here ya go. (And if you weren't, then this is just for posterity.)
1. So she leaned down and bit me, and at first I was so shocked and startled by the pain I didn't do anything. Then I said, "Hallie, let go of Mommy." That didn't work, so I pinched her cheeks together and said, "Hallie you need to stop biting Mommy." I kept holding her jaw until she let go. (The suggestion to put my finger in her mouth was an interesting one, which I have since tried, and she just bit down on that finger as well. Maybe I did it wrong?) So then Devin took her out into the hall.
2. This is a scene we have almost daily at our place. Depending on what she's been doing and how irritating/ inappropriate the behavior is I do different things. If she has, say, been hitting me in the face or pulling my hair, I usually talk to her about "nice touches" and holding her hands I show her how to softly touch my face, and my hair. Then if she keeps doing it I pin her arms down to her sides, clamp her legs down, and hold her tight and talk to her about how that hurts people and isn't nice. This definitely gets her attention and the behavior stops (at least for a while). If she has been screaming just to scream, or dumping her water out on the floor just to splash in it, or pulling the stuffing out of the couch, she goes in her pack n play in the laundry room for "time out". This is the one she doesn't seem to get quite yet, and sometimes she spends a pretty lengthy amount of time in there. But I figure at least I get some peace from the screaming. (She's absolutely silent while in there... that's why I think she doesn't get it. She just hangs out and waits for me to come back.) As for why I want to punish her, I think it's important that she learns not to hit people and pull hair, etc. and I need her to understand that when I say no she has to listen to me and stop, because someday she may be wandering toward the street or something and I need her to know what "no" means.
3. Ah, this was a classic moment. I do normally let her help, she peels the carrots and we put her up on the counter (closely supervised of course) and dumps flour in the bowl when I'm making cookies etc. But I was chopping onions and it was hurting my eyes so badly I didn't want to expose her to that, and the crock pot was already on and I didn't want to have to deal with keeping her fingers out of that - not to mention I was using the big knife to cut the vegetables and I didn't want her fingers near it. So on the floor she stayed, where she was very unhappy not to have my undivided attention and refused to go play with her toys. When the meat leaked everywhere I just stared at it like, "et tu brutus?" and just tossed it into the electric skillet. The rest as you know happened as it did, and then again I just sort of stared at the chaos around me for a second like, "really? this is going to be my day?" and then I washed my hands, picked up Hallie, cleaned up the blood as best I could trying not to get bleach on anything but the surfaces that needed cleaning, and finally went to look at the meat, which hadn't burned like I thought it was. It's hard for me to hold Hallie for very long right now though, between the belly, my back hurting, and the hernia I can only put up with it for so long, so she did have to go down again which she didn't like. I am curious though, how does it work when you put the meat in frozen? That's what we do when we cook something with chicken in the crockpot, we just throw in the frozen chicken breast and then right before serving take out the chicken, tear it into pieces with a fork and knife, and put back in the pot. So with the ground beef do you toss it in as a frozen block and then pull it out and break it up later? Let me know.
So, that's what I did - for better or for worse. Thanks again for your insights, guys!