Mazda (Ranger) pickup question

I just purchased a 1997 Mazda B4000, 4.0L V6, 4WD, 5-speed -- I have some questions and hope someone here can help.

If you have a similar truck, Mazda or Ranger:

1. What is your clutch life? When did you replace clutch plate or clutch master or slave cylinders?
2. As I understand it, the transmission has to come out to replace the clutch slave cylinder -- right?
3. The owner's manual does not say anything about this -- but -- do I need to put it into 4WD every so often to keep the transfer case seals and front hubs lubricated, or, are they lubricated sufficiently in normal operation? I don't do a lot of 4WD.
4. I don't see anything in the owner's manual about valve adjustment so I assume the truck has hydraulic lifters and I don't need to worry about valve adjustments ( I'm an old VW Beetle owner and valve adjustments are key to keeping the Beetle engine happy ).

Any other comments?

Thanks.