Once your auctioning operation reaches a certain size a second account becomes an invaluable tool. It will allow you to run auctioning scans, shopping scans and collect mailboxes while playing your main. I strongly suggest buying a second monitor as well. This will help you really unlock the benefit of a second account. For a detailed guide on why and how to set it up check out my post on the subject.
The guide should advance to the point where you are in the zone's progression. There are a few steps that can-not autocomplete and they should (hopefully) have comments to the effect of -- you need to manually check this step off. -- For some reason you have to click these steps off 2-3 times to work. (the first time will move the tom-tom arrow, the 2nd time unchecks it and the 3rd click advances the guide).
This can be a little hectic if you're on a PvP server since most level 50's are in this zone, but that's for a good reason. There are several quests for both Horde and Alliance but among the better ones are the Cauldron Quests. There are four of these, I believe, that will end up giving you good experience. Complete as many quests here as you can before we head out to the next zone.
Some addons are standalone, and are able to run without any additional addons being installed; others can require certain other addons to be installed to work at all, or integrate with other addons to provide additional functionality. Collections of addons that have been put together to form a coherent user interface are sometimes referred to as UIs.