KZ1100 Shaft rear wheel removal

Getting ready to remove rear wheel and rear drive and replace it with a lower (numericaly) geared KZ1000 rear. Couple questions..
Ive never pulled a wheel off of a shafty .. will there be mess from gears ? Should i drain oil first?
Is there a gasket between 4 bolt flange where rear diff bolts to swingarm or just silicone ?
Anything else I need to know ?

No gasket. No, you don't need to drain any oil, just slide the wheel off the gear, If your removing the bevel box you also don't need to drain any oil but remember which way the shaft spring goes