Roger,
I think both effects you are looking for can be easily rep-licated using epoxy putty. I've modeled seats before with ripped covers, exposing the horsehair (or straw) stuffing, and it was not that difficult. First, I sculpted the seat cushion to its finished dimensions with epoxy putty, then using a fresh No. 11 blade I cut slightly into the seat to replicate the rip or tear. Easing the blade under the rip I then gently lifted the edges of the putty up and away to further enhance the torn area. That exposed the stuffing which was simulated simply by using the tip of the blade, a needle, or, my favorite tool, a scriber. Using a careful touch you can stipple that area and flicking the putty up in small controlled movements will give you the irregular texture of batting. It may take a bit of practice, but it is an easy method to master.

Mike Kirchoff

How about course steel wool for the horse hair?