1. No conflicts. They are separate building, and have the same adventures as the Castle - they just take double the time
2. I'll write a summary below for you. The
Adventure Guide has the split about what's available in the 3 castles (Adventure Time: Castle/Keep - 1 day | Barracks - 2 days | Haunted Keep - 2 days), but I might add it elsewhere too
3. Exactly the same as the Castle adventures
4. No, the barracks and the haunted keep never have event adventures; it's a level playing field in the castle only. Same for additional adventures for main story goals. They are not available in the Barracks.
The only exception I know of that (I can only recall this for a couple goals) is that when you have to adventure say 10 times to clear a goal, collecting from the barracks adventure will count. I've always made a special note when it does count towards one of those types of goals. Eg is the Dragon Trainer goal I'm working on now.
Search the Ancient Vaults - Adventure Time: Castle/Keep - 1 day | Barracks - 2 days | Haunted Keep - 2 days
Hunt Roaming Bandits - Adventure Time: Castle/Keep - 1 day | Barracks - 2 days | Haunted Keep - 2 days
Explore Dark Caves - Adventure Time: Castle/Keep - 1 day | Barracks - 2 days | Haunted Keep - 2 days
Feral Lands Adventure - Adventure Time: Castle/Keep - 1 day | Barracks - 2 days | Haunted Keep - 2 days
Traverse the Desert Sands - Adventure Time: Castle/Keep - 1 day | Barracks - 2 days | Haunted Keep - 2 days
Envoy to the Plume Hive - Adventure Time: Castle/Keep - 1 day | Barracks - 2 days | Haunted Keep - 2 days
Envoy to the Fur Burrow - Adventure Time: Castle/Keep - 1 day | Barracks - 1 day | Haunted Keep - 1 day
Dispel the Love Magic - Adventure Time: Castle/Keep - 1 day
Go Fishin' - Adventure Time: Castle/Keep - 4 hours | Barracks - 8 hours | Haunted Keep - 8 hours
Dive into the Abyss - Adventure Time: Castle/Keep - 1 day | Barracks - 1 day | Haunted Keep -
not available
Toadstool Forest - Adventure Time: Castle/Keep - 2 hours | Barracks - 4 hours | Haunted Keep -
not available
My opinion of whether "Is it worth it?" is yes. I am continuously adventuring. The drops and the gems and the additional energy it provides, especially box drops like fruit trees and sheep and cows and glimmertroves (which only can be purchased otherwise with gems) is so helpful, even for well-established kingdoms. If you have a few feast droppers (and there are quite a few now) then it's much easier to keep an adventure going in both or all 3 buildings. Initially it seems like a big spend (which it is!), but I am glad I did. Pretty sure this was the first things I ever bought with gems going way waaay back!
Other players have never bought it and don't feel like they're missing out. I guess with all items you can purchase for gems, you have to decide if it's going to enhance your game play for the way you play to make your decision. Would love to hear what you decide and other players will post their thoughts too. I'm sure there is a dedicated thread buried somewhere, but it's ok to discuss that here too.