You can generally do a bit of optimising following skinning/animating, though not much. With skinning, you will almost certainly have to redjust the UV map following any removal of faces/vertices - but it is generally pretty straight forward in what needs to be done.

Animation is a bit more complicated. Chances are you are going to be animating with bones (even if you descide to save it out as vertex animation later), so it makes life a lot easier. You will still probably have to readjust the weighting on the mesh to correct any errors which occur due to removed faces.

Just looking at the wires - although it looks as though you are probably pushing 3500 polygons you should have no problem getting it in line. A number of the faces on the legs themselves will not be seen ever - so you will be able to clean those up quite easily.

The clothing will take some creativity, though you can reduce it by about a third and loos no smoothness in the animation.