I'm sorry op, it must be very difficult.
It was interesting what you said about if only tantrums were about wanting things, such as sweets, as that could be easy to fix. Do you mean you'd fix that tantrum by giving in and giving her what she was tantruming about?
I (generally) would never reward a tantrum by giving in, because that can reinforce the idea that tantrum = get what you want. I'm afraid in the hair bow case I'd walk away while she was tantruming and tell her that she could come and find me when she'd calmed down.
Also, in the party example, if it happened during the party, I'd take her to one side, tell her such behaviour was not appropriate and make her sit it out until she calmed down and then (if possible within party activities) take her to apologise to the person who gave her the prize before letting her join in again. If she wouldn't, we would leave (apologising to birthday child's parents as we left). If the prize tantrum happened at the end of the party, I'd tell her that it wasn't acceptable and that when we got home she'd go to her room until she'd say sorry (to me).
As for the walking refusal, I'm afraid I'd get oh to pick her up whether she liked it or not, then take her to the car/home.
I'm not trying to be critical of you, just explaining how I'd handle it. Perhaps I'm a too-harsh parent, but I think it's my main job as a parent to teach my children how to be considerate and well behaved individuals (wherever possible).
The other thing I'd mention is that I'm also a bit judgmental of "soft parenting". We know a couple of children whose parents use this style and their response after their little darling has hit my child with a spade (!) or punched him full on in the face was so wishy washy I was incensed. If the boot was on the other foot I'd have made my child apologise, removed him from the situation and apologised to the parents. These parents did none of this and I vowed never to leave him alone ( i.e. Without me/oh watching closely) with anyone of them again.
Good luck, I hope you find a way forward.