I was kindly sent 3 rules clarifications from Cafe Games, that I thought I would share.
In a message dated 8/21/2006 1:21:30 AM Eastern Daylight Time, firstname.lastname@example.org writes:
1. Can players move their pieces through/over other
players pieces (not cities)?
No, only through their _own_ cities.
2. If a player has only 3 hexes with pieces in
them, can you still attack their cities?
No. They are immune to attack if their tokens occupy 3 or fewer hexes.
3. When a city is being attacked, can the owner of
the city declare the terrain type to be "mountain",
effectively making no cards effective on the basis
of terrain type?
By the way, you can read more about theses rules questions, and more, on the excellent website www.boardgamegeek.com. Just search for Tempus, and scroll down to the forums section on the Tempus page. There you will see several discussions on the game.