bob,
do a search for flex disk, there is a post that has great photos.
1. the grease fitting I assume greases the spline.
2. good question, you could remove the grease fitting off the center bearing for comparision, they are most likely the same
3.once you get the old disk off the sponge bushing goes on the shaft and the o ring will go between a metal plate and the end of the shaft.
the post, if you find it , will have great instructions and photos.
the post will also provide you instructions on proper bolt installation.
matt
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230