Isuzu has a couple of wagons that can be jacked up that get pretty good gas mileage that have 4 wheel drive.
any hub that expensive should be able to be overhauled... I've never seen one that doesn't hold the bearings in with cones. To open it up you'd need cone wrenches though. I'd need a visual to tell you more In this case I would take it to a bike shop,...
yes, you can use the steering wheel on dirt. i use mine all the time.