Greg,
It has been about 30 years since I did these operations as repairs (more recently, I've done these operations during a rebuild/restore). My memory is often lacking, so let's hope someone with more recent experience will answer.
1. Yes, doing any one job puts you in a position to do the other jobs - might as well.
2. The trickiest job would be the rear seal, but it is worth a try - just doing the bottom, even.
3. The speedi-sleeve goes over the front of the end of the driveshaft (it "repairs" grooves in the driveshaft by giving a smooth surface for the seal that is mounted in the cover). I am pretty certain this can be installed without removing any timing gears.
4. 4 hours - if you are good and if you are lucky that everything comes off and goes on "by the book". Also, there is some sort of glue/cement that comes with the speedi-sleeve (I think) and this might have to cure.
Tim
