What is the best way to import my 2d image of my character into unity and what is the best way to animate him?
Check out this thread on Evac City, the tutorial has a good section on animating 2d characters.
Brady Wright's Sprite Manager (here, on the wiki) is designed to allow you to manipulate 2D sprites like this.
Usually you would want to set all the frames of animation for your character into a single "sprite sheet" laid out in a uniform grid. You can then set up animation loops in the sprite manager by giving it specific ranges of frames to animate through.