Greeneyedzombie
King
What is the conquer event? haven't played yet as the portugese. Is that the event you get a nice army (canon, knights pikeman and muskets) next door to the aztecs? Wich means the end of the aztecs btw. I think its a bit to strong.
I can only roam during turn trasaction when nukes are falling, no other time. 
BTW: civ after having its spawn area should capitulate very easily. And after returning cities should have their capitals back in their Spawn area (my vassal- England have capital in New York- it protected them from losing that city to Americans
).