Front differential questions, need help w/problem

Hey everyone,
I am trying to trouble shoot a bugger of a problem. I won't bore you with all the details but have a question or two for the group.

My Tacoma has been through 3 front left axles. So that leads me to the following questions.

When in the air (on jacks) will both front wheels of your Tacoma spin freely with no binding or issues with the inner CV joints? (my left binds, but not when there is weight on the a arm, not sure if this is normal, I don't think so)

Has anyone experienced problems with the front differential ADD (automatic differential disconnect) not disengaging fully?

Has anyone experienced a bearing failure in the front differential causing binding in either axle?

How hard is it to rebuild a front differential?

Thanks in advance for your answers!!!

Clint