96 golf few ?s

barely bought 96 golf gl, so stated changing part. When I got to the spark plugs, 3 of them were fine and one of them was really charred and black. I dont really know much about cars, so is that something to worry about? It runs fine, starts up on the first click it's just kind of odd to see one burned out plug and the rest clean.

Another Q. I'm getting oil on my clutch plate, so that means one of my seals is leaking. So might as well replace the whole clutch, its about time 109000miles. Is anyone familiar with SACHS clutches. Do they suck compare to other ones? Found some on ebay and was wondering if it was worth it.