THe plugs look like they are a bit hot/lean. Not to bad though. As long as peices arent missing and there arent and specles on them you are ok. Just make sure that basic maintenance (fuel wise) is kept up.

As for the filter, K/N is definetly worth it if you plan on keeping it. They are the best hands down. Gap the plugs to .044" and you are all gravy my man.