Some of your answers are going to depend on what class you're playing. For instance, DRK has a full toolkit of enmity generating tools out of the box. It also might be tougher for a first time tank. I recommend looking up and reading a guide specific to your class.

Tanking skill and tanking aptitude are really two different things. You will probably know within your first few dungeons whether you have the aptitude ("I want to do this.") It will take longer to develop the experience and comfort level to call yourself skilled ("I am good at doing this.")

Basic rule of positioning is keep your mobs faced away from your dps and healer. Open with your ranged move, close the distance, aoe aggro generating move (flash, overpower, unleash) a couple of times, then rotate enmity generating combo moves on all the mobs because your aoe dps will be hitting everything.

Use of cooldowns is really something you have to develop a feel for with practice. Again it depends on your class.