Dave is located on the rooftop southeast of Makayla's shop in Halai Village. Talk to him to start the quest. He'll ask you to kill the thug below. Open the gate and kill the thug. Return to Dave to complete the quest and get your reward.
After completing “Where the Dead Live”, you'll find Rose in the second floor of the Halai survivor camp. Talk to her to start this quest. Make your way to the Ocean View Bungalows and enter the deadzone. Be prepared and don't startle the zombies outside. There's a butcher and a boss zombie named Eduardo “Quickdeath Petoia”. It will be a good idea to lay down a mine or two by the door way and have your Fury attack ready. After killing the boss zombie, you can pick up the antidote from its body.
Defeat Eduardo “Quickdeath Petoia”
This is the boss zombie inside the Ocean View Bungalows deadzone and will drop the antidote needed for the sidequest of the same title.
After completing “Where the Dead Live”, you'll find Dr. Jane Hanson on the lower floor. First, head to the alternate shop run by an NPC named Makayla. Next, you should see the hospital/clinic where you met Dave for the sidequest “On the Set”. Climb the ladder to reach the rooftop then head southwest until you see a blue-painted building. Barge in the door and kill the enemies inside. Be careful since there's a suicider there as well.
Talk to the doctor to update your objectives. You now have to find the medicinal mushrooms inside the Lonely Cave, a transition area north of the marina.
Once inside, kill all enemies inside. Be careful of the frenzied infected. If possible use meat baits and grenades to take them out easily. Once clear, gather all glowing mushrooms in the cave then loot all the items. Leave the cave and hand the shrooms over to the doctor in Halai.
Talk to Houston inside the Halai Survivor camp to start this quest. This is a repeatable quest that will require you to bring him painkillers. He will reward you with considerable cash and experience.
Talk to Maggie inside the Halai Survivor camp to start this quest. Before heading to the jungle, I suggest taking the other sidequest in the village called White Line. Once ready, head to the tree house within the green circle in the map and climb to the topmost part of it. Grab the Ripper Mod nearby and read the letter on the floor.
After listening to the recording, you have to head west this time. It will be easier for you to just travel back to the marina and use the fast travel back to the Paradise base camp and head north from there. Upon reaching the camp, read the letter inside the tent.
Head to the next marked location and enter the cave. Be careful since there's a butcher inside. After killing it, find the small campsite with a campfire to find the message on the ground. Your objective will then update and require you to go to Henderson. If you don't have the means yet as part of the story, save this quest for now.
Once you've reached Henderson in Chapter 8. the quest will be updated. You'll have to search for the hideout in the shopping district. Enter the deadzone Motel Safe Haven and clear the room. Find the letter in the last room to update the quest. Return to Maggie in Halai village to complete the quest.
Look for Bruce inside a house with a workbench in the northern part of the town. Talk to him to start this sidequest.
Head to the Hanging Joe treehouse in the jungle and enter the dealer's house there. Kill the boss zombie inside then examine the covering in the corner of the house. Use the ladder to go down and kill the two walkers inside. Grab the white stuff on the table, as well as the third Secret Files in the shelf.
After picking up the drugs, you have to take the fake drugs as well. Make your way back to Bruce and hand him over the goods to complete the sidequest. Bruce will also open up a light weapons shop.
This quest will become available after the main quest “The Ritual”. You can now also fast travel to Mataka Village. Talk to Marcus Villa and kill him to complete this quest.