"A Warm Welcome" and "Plants of Zangamarsh" are not listed as "to do" spots, as the mobs for them spawn all over the zone. You do, however, need to finish Plants of Zangamarsh before circuit2. When you first step into the zone you'll start seeing ground spawns called "Glowcap", they're clickable mushrooms. Loot them and keep them, you turn them in later.
Boglash paths from here to the south. He's a level 61 elite and he is semi-difficult, but definitely do-able.
Simple quest.
While you're here, kill naga for awhile for "A Warm Welcome". Occasionally, the Steam Pump Overseer's will drop an item that starts a quest chain. If you finish "A Warm Welcome" before getting that item, don't bother hunting any longer for it. You'll have more chances during Circuit2.
Make sure you do this last because it takes you back to the city.
Simply click the amulet in your inventory and it auto-flies you around the zone.
This quest may require Friendly rep, I am not sure.