Unity2D animation and sprite layout

I am starting to prepare for a 2D game using Unity and wanted to know a few things about how I should approach the artwork and animation. Below is a quick image of the style that I am trying to go with for my project. Concerning animation, should I make each section a separate sprite (the head, eyes, arms, legs) or should I do each joint (the four squares for the arms, each eye, etc)? I want the animation to be kind of fluid and not quick costume switches. Another thing, what pixel size should I make the sprites for Unity? I was thinking of making 32X32 for something like this but I'm not too sure. Also the Unity pixel per unit size would be helpful. Thanks!