When trimming dead roots, only trim the ones that are black or mushy. The firm ones are healthy roots. As for the subspike, (and I'm going to get beat for this) I'd say leave it. Your plants appear to have plenty of green roots and nothing looks like rot or disease. Your plant is just severely dehydrated. I suggest repotting the plant and increasing your watering habits. If you're watering once a week now, make it two. Do use the skewer method mentioned and in a couple of weeks, we'll go from there.
The little booger is adorable!!!! :P