If you work slow it might take you 10 hours. A professional should be able to do it much faster. I recently did all the things you are concerned about while also removing my heavy 4 speed trans and clutch assembly so I could replace the pilot bushing. I did all that in under ten hours work time but if you add up the time I spent cussing and sweating on my back under the truck it was probably longer. I got estimates for this larger job than what you are talking about that ranged from $500-1200. The $1200 guy made it clear he wasn't keen on doing the job. You do not have to remove the rear axle to do this, just rotate it back on its pivots. Don't have the truck supported by the rear end. None of this address replacing the torque tube bushing which has no effect on external oil leaks.
