The small hole is a thick washer that should knock out and fit right up to the new U joint half.
I dont like the new method of retaining the spider , with the bent metal under the bolts , I much prefer the old cast item , much less "give" in it. Check the bolt strength , I have had a couple fail with mild steel bolts , really only lasted months. Need really good grade bolts.
The rocker springs and washers are there to stop the rocker moving sideways on the shaft .
Don't know about the oil line .
