I really enjoy running dungeons in mmos. What I don't really enjoy is doing solo story missions. I like team work and showing off my skills in pve. Not saying I am very good but I still have fun.

I have read a lot of random bits of information. But every source I find seems to have a little different opinion on it. My main question is this.

Will I be able to level my character in a timely manner using mostly dungeon runs (instances) for a source of exp?

The first dungeon is at level 12, give or take, so you'll need to get to at least level 10 I think to run it, unless you have friends who are willing to take you at a lower level. Once you complete the dungeon in your zone, the dungeons in the other faction zones will be available to you (the level 12 ones only). I don't know what level the next set of dungeons are at, but I'd imagine you'd have to do some questing or pvp to get high enough to do them.

I don't think you'll get enough xp from them to really level all that much. Killing mobs doesn't give a ton of XP and any quests related to the dungeon may not be repeatable.

Even if you could, you are missing out on other things like progressing the soul magic tree which comes from completing the main quest line, and mages guild whivh comes from reading lore books found throughout the world.

Yeah I understand I can't get to them until level 15. I am ok with that because It gives you a chance to learn the game mechanics. Its just the main reason I play mmo is for instances. I heard from one source that repeat dungeon runs don't offer much exp. Then I heard from another source that packs of mobs do offer decent exp.

Creature kills don't give much XP, and that includes the ones in dungeons. The first time through a dungeon gives a large chunk when you complete the quest inside (which always amounts to "kill all of the bosses in here" in whatever guise). You could keep doing dungeon runs over and over, but it would be a very slow process. By and large, XP gain is a matter of quest completion.