I am very new to the game, a friend helped walk me through a few basic things but I am a bit confused on some.

As a caster (conjurer) When I try to attack something do I always have to press enter after I have selected my skill or is there a way to make it always automatticaly cast after I have selected the skill.

ie. press 2 (fire), press enter to use fire.....(seems a bit silly to have to confirm my choice after I have choosen it lol)

I would like to become a healer, can I be a DD and a Healer or do I have to stick with just Healer?

Is there a friends list?

What is the big green button for (AOE) do we have to decide if a skill should go single target or aoe? or is there another use for it?