How can you travel from Nightfall to Factions?

I just wanna know b/c you can lvl up sooooo much faster in cathan than elona!!

Once you do the consulate docks mission, go back to kamadan and you'll have two new missions, one to Lion's Arch and one to kaineng

You need this Quest first:
http://gw.gamewikis.org/wiki/The_Time_is_Nigh

To get to LA you need the following Quest:
http://gw.gamewikis.org/wiki/Terror_in_Tyria

To get to Kaineng you need the following Quest:
http://gw.gamewikis.org/wiki/Plague_in_Cantha

A Faction char can go to Tyria and how?

Wiki is your friend

http://gw.gamewikis.org/wiki/Port

Yes sure it is!Thx!