2 things :
- copy images to new folder structure instead of legacy one since it's a PS 1.5 branch
- don't create all sizes of images at migration, there's an Admin controller for that (Admin > Settings > Images). That's speed up the import and remove duplicate code (less code to support).
+ some cleaning of unused variables
Imported categories was affected to Root category instead of a Shop's Home category.
I took the first shop home category is by default.
Maybe adding an option to choose the shop where the datas should be imported.