Prophecies/Factions/Nightfall

Okay so, I bought GW:NF.

If I want access to the Prophecies/Factions campaigns, will I need to install both of them, or simply add their access keys to my account?

Same for EotN, will I need to install that or just add its access key?

You just add the access key - then do -image or just download the areas as you get to them.

You don't have to re-download the client or anything, just add them to your account via the login screen, and then load up areas as usual (going into each place and then it loads there) or you can use the -image tag.

More info here: http://guildwars.wikia.com/wiki/-image#-image

Hope I helped