I was going to do a post in regard to the doorway this weekend, i should do that today actually since i'll probably be home a good part of the day.
On the time period thing, I was considering that as well since the persons interested in time travel may have other times they'd like to visit with their chars or simply create chars for a particular time. Like with the dark ages/medieveal, i've also got some interest in the Victorian era.
What we can do is run a game on the dark ages and people can still time jump to wherever they want on this board whether that period, victorian, civil war, any time they wish. Leaves it open to everyone to do their thing.