How should I import models from Blender for animations?

I have a simple model that is made up of all cubes/rectangular prisms, kind of like a Minecraft guy. For example in blender, the feet are each one object with a certain pivot point that I use to rotate it for animations, and the neck is one object and the head, etc., so there is like a hierarchy of different body parts. But I have heard that when you import blender to unity it is better to have one object (for performance) but then how can I do my animations?

Generally animations are done by skinning a mesh using bones. I would suggest looking up how to skin a mesh in blender for more information.