What I found a bit... convoluted was some of the wording you chose to describe the controls, not the idea in itself. Like, your last two points for instance could be summarized with "the party should move in formation", which once again is exactly what any other RTS or game of this type does.
Only the last point is about formation, and by that I mean the relative position of each character within the group. Some games allow to change it (V, column, and so on are the examples I gave, and are typical combat formations). So yes, the party should move in formation, that's for granted, no need to mention it. Should we be able to change the formation, I'm not sure.
The point before last is not about formation, it's about the group, I thought the description was clear but to elaborate: in some games, when one of the group changes area, or even passes some trigger, the other characters respawn too and the group counts all the characters again. For example in Kingmaker, when you don't select everyone and enter a cave, everyone spawns in the cave nevertheless. I'm not sure how Larian does that in BG3 anymore, in D:OS2 it wasn't the case, sub-groups remained at their respective locations, it feels more realistic.
The third item is about how characters move. When you select another character in Larian games, he/she becomes the "leader of formation" and all other characters do crazy stuff, running all over the place to fall back into the new formation. Doing so usually have them walk into fire, trigger traps and all sort of nonsense, it's obviously not what the player wants. So they should stay still when the selection changes.
Anyway, scratch that. To keep it simple, I just hate how they do it right now with the chain gizmo because it's not easy to manipulate, it's unnecessary, and leads to side-effects like the characters running in all directions when the group leader changes. With the shift-select all other games offer, it's simple, there's no "leader", and it's intuitive.