Sometime in the near future I i will be replacing the axle support bearing. The question is if I have to drain the automatic transmission to do it or can I pull the axle shaft out without having tranny oil spill?

 

You don't have to drain the transmission. On my one car I had oil dribble out once I removed the oil seal. On my other car I only had a couple of drops come out but I also had the car jacked up higher.

 

There no axle seal per se, there a transmission seal which is the output seals on both sides, if they are damaged, i would recommend to replace it.