If you've never done arenas via LAN, you really might want to try it. Of course it's much easier to communicate when you're speaking to someone right next to you and can see their screen to get a different perspective on the battle. You can also learn fascinating information about their AddOns and how they interface with the game.
I had a friend come over to play and was absolutely shocked when I saw him clicking away at his spells and abilities instead of using hotkeys. When I first started playing WoW, my mentor would swat at my hand with a wooden ruler every time I clicked where I should have mashed. (Ok, it was actually just a stern glare- no ruler.) I spent several hours with my fledgling Priest killing Scarlet Warriors and learning the motions for keyboard controls. I quickly learned that Q, W, E, A, S and D are the most valuable real estate on the keyboard. Since fractions of seconds can be critical, it takes a relatively long time to move around the screen with a mouse.
I made numerous mistakes in those early days, but I would never go back to clicking. I have almost every key mapped now and try to keep spells with similar effects consistently mapped across my characters. I can't imagine healing an instance or an arena by clicking. It took another training session to learn to control my Hunter's Dragonhawk with hotkeys, but now it's pretty natural- even habitual.
How do you interact? Do you click or key?