For "To Kill with Purpose" you need togrind the living rot rather quickly, but once it's coagulated you don't need to worry about timers.

"Un-Life's Little Annoyances" "Demon Dogs" "Carrion Grubbage", don't worry about completeing them now. Just grind on your way to the next step.

Before you cross the gorge, you need to have 20 Noxious Plaguebats and 5 Plaguehounds slain.

Also finish up Carrion Grubbage.

The best way I found to do this quest is to clear the stuff on the western edge of the area. There's a little hut with two trolls in it, as well as a troll that wanders by. When I killed the three of them, I pulled Infiltrator Hameya up by the wall and fought him there. If you fight him down in the center area where he spawns(by the graves/dirt piles) you can and usually will get too many adds. He's also marginally harder than most things his level, so you might want to blow a cooldown or two to prevent the (long as hell) corpse run.

The Scouts will run to the nearest non-roaming mob's spawn point and attempt to get help, so only pull the scouts when everything around them is dead.

Click the bigass termite mounds that you find in the plaguewood to collect termites.

I tend to grind a little bit between this and the next 2 steps, just because there's nothing I like killing more than the damned dirty undead.

Accept "Agustus' Receipt Book".

You need to go onto the top floor, it's in the furthest-back room, you'll find it.

Return to agustus and turn it in, then continue on.

Be careful, there's an elite spider in this cave and he's an asshole.

Skip the follow up, it's too damn hard.

Loot his head for the quest "Zaeldarr the Outcast"

To do this quest, I back into one of the corners farthest frmo him and pull one of the trolls. I almost always get all 3, but not Zaeldarr, which is what I hope for. I blow cooldowns, potions and use all the tricks I have to kill the three trolls at once, then kill Zaeldarr alone.

Hearth to Undercity, turn in "Better Late than Never" in the center-ring area(ask a guard for the Guild Charter area and you'll see it). Accept "Jeremiah Blues" and turn it in at the cockroach vendor under the walkway leading up to the bank. Accept "Good Luck Charm". Return to the bulwark and start circuit 2 in Western Plaguelands.