Campaign Questions

I own the Prophesies campaign, and am considering buying either Factions or Nightfall. But I have a question: If I bought an additional campaign, could I transfer my level 20 Prophesies character to the other campaigns? Or do I have to make a new character for each campaign? Thanks!

makes sure that you add the CD key to your current account... This is the main failure most make the first time

Anyway, once you add the cd key, take any of your current characters to Lion's Arch and you'll then be able to do a couple of missions to get over to the other continents (dependant on what chapters you bought)

If you add the new key to your existing account, your old characters can play the new campaign as well.
You will get 2 additional character slots for adding a key.
If you decide to create a new account with the new key, you will get 4 character slots, but all your old character won't be able to play the new chapter.

If you buy additional campaigns and link them to your current Prophecies accounts, you'll have access to those continents with all your characters. Think of it as buying an airplane ticket for your Warrior/Mesmer/whatever. The character is still a Native Tyrian, but they can now travel to Cantha or Elona and participate in adventures there.

You'll also probably want to create natives in the new campaigns as well. There are some professions such as Assassins and Paragons that can only be primary to natives and there are some beginner quests that will only be available to natives.