2) Have you been able to takeover/giveback a virtual interface? Treating it like a "normal" interface doesn't seem to work and I haven't been able to find any special instructions for this.
Virtual interface (vif, Etherchannel, link aggregation, your-name-here) takeover/giveback is not supported in 5.2.x
The 5.3 release supports virtual interface takeover/giveback.
/sas