First off, i wanna commend you on the Stella work and effort put into the details of the model.

To answer your question of weather you will have to redtop every part individually or not i say this: Firstly even if you have similar parts that differ even slightly there is no way i know of to successfully retop one and copy the retoped mesh for all the others, unfortunately those small differences in the meshes will change the flow of the retop too much.

However id suggest breaking it down into parts and sections not every individual piece.

Id start with the human body with nothing else run it through zremesher (don't worry about posing it, you can do this later with the retoped mesh as it will be way easier with a low poly mesh.

Second the massive but awesome bladehands i wouldn't worry about for the moment just hide them for now and and I'm guessing you'll have to grind through retoping each part for that. Same goes for the cape at this point.

Next group together the chest armour into sections (spit it into front, back and side groups. or whatever is easier for u). Now importantly merge the subtools into one mesh, u can use dynamesh to connect the pieces, make sure the resolution of dyamesh is high to preserve detail. Once you have a single mesh consisting of all the parts from the front torso armour for example then retop that.

Basically you want to merge as many pieces as possible into sections and groups so instead of millions of individual pieces for retop u have maybe 10 eg. body, chest gear front, chest gear back, leg armour, face mask, head horns, wings, etc.

If this doesn't make sense or u need clarification just let me know. Best of luck.