Prophecies to Factions

If you played through Prophecies and recently purchased Factions, are you able to take your Prophecy characters to Cantha?

If you have linked Factions to your Prophecies account, you can take your characters to Cantha and vice versa. Talk to the skills guy in Lions Arch, he'll have a new quest for you once you have done so.

if you have linked your accounts you can.

Canthan characters can also be taken to Tyria, as well.

yea

how about if i have a US version of Faction and thinking of getting a UK version of Prophecis? will it work out?

Yes it will work out.
It does not matter what key you use.
Just make sure that you link the accounts and do not create a new account.