Vladlen Great Job!!!
I don’t like zBrush. I prefer Autodesk products. Definitely I agree with you and I recommend RAWs than JPG. You don’t need Lightroom, RAWTherapee is good enough as Blender and for free:] You can bake AO or normal maps in Blender as well. Blender has good retopology and UV tools as well.
https://blendermarket.com/products/retopoflow/
Ok this is external plugin but much cheaper than zBrush, Mudbox or Maya. In my opinion, maybe I am wrong, but it is much easier to create low poly meshes objects like yours or ShadowTail than gothic or renaissance buildings with many details.
Once Again Great Job:]