Wow--you've got your hands full. I've been working with kids for a long time, so let me say first off--while you haven't seen children act like this, I have. A lot.
Part of this is what's happening at your daughter's age--she's figuring out how much autonomy and independence she has in making decisions which affect her, and is trying to exert her power. It might be in a manner we adults find frustrating and pointless, but given her age--and the very real inability to reason in a way we adults can relate to-- it is the only way she may know how.
Brain research shows that the immature brain of the child processes disappointment or loss in the most primitive "pain" regions of the brain. To better explain it, imagine yourself being given disappointing news--let's say your babysitter cancelled and you had plans for a night out. You, as an adult, will likely be upset and maybe even a little crabby about it, but you will may be able to accept this disappointment and rethink your evening plans. A young child, on the other hand, might very well experience this as a truly overwhelming pain. It is very real, just as we might feel a very real pain in a heartbreak or a broken bone--it stimulates the same exact places in the lower brain. Hence, the fury and acting out.
I have two books to recommend, and techniques I have found helpful. First, the books. If you are interested in more about the very real affects of the brain processes of the developing child, "The Science of Parenting" is a great start. Despite the high-falutin' title, it's very easy to read and makes such complete sense it's astonishing. Secondly, I'd check out the Positive Discipline books and website. Some of our interactions with our children depend a lot on nuance and positive persuasion (not all, and I'm certainly not saying that you are doing anything wrong, please do not take criticism away from this), and this book puts forth ideas that help empower our children to take an active role in working through problems.
Two things that have helped me incredibly over the years--first, I refrain from asking children 'if' they want to/are ready to do what I am needing them to do. Instead of "Are you ready to do X?" I say "It's time for us to do X." When we state that it's Time To Do, we refrain from offering the child an opportunity to say NO. (They might still say no, but we are owning the decision, which is more honest.) Second, I nearly always give a "How Choice": "It's time to wash your hands. Do you want the pump soap or the bar soap?" or "Would you like to wash up at the bathroom sink or in the kitchen?" What happens here is that the child (hopefully!) is quickly moved past protest to being thoughtful about how they would like to approach it. Instead of debating, they are invited to participate. I've also discovered that when given a choice in How to do a task, some children create come up with very reasonable third options. I honor these whenever possible, because this is at the crux of their development--positive experiences in problem solving=practicing autonomy.
I do think you are correct in giving clear boundaries and keeping your other children safe. I really feel for you too, because I know firsthand how exhausting this can be, especially if everything feels like a battle, day in and day out. I have nothing else to add other than that this does pass. I've known many terrific children who went through stages such as these and have turned out to be lovely young people. Last to add, your daughter is expressing her anger and pain, so try to remember to let her have her emotions while correcting the actual physical behavior. It's like the old saying--feelings are okay, it's what you do with them that counts.
Best wishes--hang in there!
H.