Thanks very much for your feedback.
Yes you can save palette per document.
I agree that this docker can use some rearrangement like for example the button for new pallete can be outside at the bottom of the docker, like it is in the layer docker. the plus icon for creating group can be different. etc.
I agree the docker resize when it is floating is cumbersome
This might not be a best solution but it can be done. Go to krita settings and uncheck toolbox and dockers in canvas only settings. This will enable dockers in canvas only mode. Then you can close the unwanted dockers and keep only the ones you want as floating dockers or fixed ones.
It would be good to have shortcuts assigned to dockers so that we can call them anytime and even in canvas only mode.
There is an old wish bug report for this feature request here - 338132 – Add mechanism to show/hide dockers floating using shorcuts and there is also afeature request for it in this forum - Shortcuts to toggle Dockers