AFAIK (based on dom2 tests) :
1) No, items or communion have no effect
2) No, it seems random
3) I think they reverse back to the base level (never tested this situation however, high lvl spells are scripted for the first 5 turns)
4) hehe, the slaves are free again, keep the protections and follow the script. Try this with a golem (comm. slave + 4xhold + attack closest) when Fire shield, Soul vortex etc are available from a retreating communion master
