On the Vortex...what does the -2D, -1D etc. stand for - some kind of countdown?
This bears a slighty longish explanation since you just unlocked the vortex. Normally, you choose one of the vortex dungeons to unlock each day, and you can play it as long as you have stamina, until the next day. The countdown normally shows how much longer until the reset.
This weekend, however, all vortex dungeons are unlocked, so their counters reflect how much longer until they close and revert to the normal behaviour on monday.
EDIT: Now, a question of my own. Can you use the same account on two devices? I would like to play on both tablet and phone, but I'm not sure if logging in with the same Facebook account on a second device will allow just that, overwrite the cloud save associated with the Facebook account with whatever is on the second device, or what.