Bearings and pinions

Hey Brian - Ready for some more stupid questions...
I do not see any signs of oil leakage at the pinion seal. However since the axle is off now, is it worth just replacing the pinion seal and nut now? I read the haines about this and it noted that I will need to remove the pinion shaft to get at the pinion seal. Keeping in mind that I know relativelying nothing about how an axle works (yet)... when I remove the pinion shaft, will anything happen to the gears? I am trying to not have to getinvolved with setting the gears at this time, any I just want to make sute nothing else will "fall out" when I remove the pinion shaft.
Next question, I do not know much about bearings; other than they require grease, some are rebuildable and some are not. I know that the onese that are rebuildable should be re-packed after each wheeeling trip and since the I do not know of the prior conditions of this axle, if re-buildable, it is worth re-packing/checking the condition of the bearings. I know the bearings on the 35 are not re-buildable. What about what would have came stock on the 1988 XJ D44? The bad part is, I do not know how to tell if my bearijngs are re-buildable or not. When the bearings do fail, if non-rebuildable, I plan to put re-buildable ones in instead; but would prefer not to have this expense at the moment if the current sealed ones are fine.