1984 Vanagon Automatic needs rear wheel bearing

Hi; I am brand new to this group and am in the process of buying my first VW since 1977. It is a 1984 Vanagon with the 1.9L gas engine
(yeah, you knew that!). It has 188,000 miles on it, the engine rebuilt 35,000 miles ago. The waterpump is gone (leaking and bearing shot) and the rear wheel bearing on one side (probably the other too) is loose. I am mechanically adept, do all my own work (mainly my K-Cars and Rampage L body). How much of a job is it to change out the rear wheel bearings?
Another question - is it possible to replace the automatic tranny with a 5-speed out of a Porsche 914 or 917? Gas the way it is it seems like it could only help. I have done an automatic to 5-speed conversion in my wife's 1989 Plymouth Vovager and it turned out pretty good, so I have an idea what is involved.
One last question - I hear that some folks are replacing the VW motor with a Subaru Legacy motor. This makes me believe there is a significant amount of interchangeability with the VW transmission, but there must be a challenge with all the engine management systems. Anyone out there know of a website that talks to this point. For now I want to keep the bus "all VW" though.
Thanks all for any responses!!!!
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