Rolling Failover is ~= Failback:
By default, NIC teaming applies a fail-back policy. That is, if a
physical Ethernet adapter that had failed comes back online,
the adapter is returned to active duty immediately, displacing
the standby adapter that took over its slot. This policy is in effect
when the Rolling Failover setting is No
Source: http://www.vmware.com/files/pdf/virtual_networking_concepts.pdf
As far as how A/A or A/S, depends on what your end goal is. The above doc explains those options quite well also.
-Cody
http://professionalvmware.com
-Cody Bunch
http://professionalvmware.com