A service manual would help a lot. I've worked with cars, boats and atvs for many years so I just wing everything. If I can't figure it out I turn to the Internet.
I'd do the easy ones, o-ring on the bearing carrier and the spaghetti seal. It's not easy to remove the drive shaft and shift Rod seals without the proper tools.
Be sure to clean the mating surfaces and apply liquid gasket aswell. Also replace the nylon washers on the drain and fill plugs. Might aswell pull the 3 flathead screws on the water pump and take a look at that while the lower unit is off too, make sure you don't lose the pin the impeller spins on.
You may want to checkout the clutch dog and gears aswell while it's open. Take some pictures as you go so you remember how it all goes back together.
