Played two beta weekends, but did not do any LFG/dungeons. I am assuming the ESO has a LFG mechanic.

Can someone describe the LFG for me? Is the queue populated per role like other MMO (tank, dps, heals)?

If so, what is the quickest que (I assume tank or heals). I enjoy both tanking and healing and I'm trying to decide on which to start with.

Thank you in advance.

Shortest wait time is having friends to start with. Dedicated healing will be quicker than tanking though, and many people are able to fill many roles at once.

Having played both, healer and tank for about 60 dungeon runs using the lfg system I could not tell if tanks or healers wait longer. Sometimes it's instant join, sometimes it's a wait of 15-30 minutes.

DPS certainly waits the longest since 90% of the times I joined two DPS that are already waiting.

Yes. You pick a role (DPS, tank or healer, or all at once) and wait for the system to find people who want to do the same dungeon. The system still needs work, e.g. you cannot select to line up for two dungeons at the same time.