Oh baby, automated harvesting is a trap. You'd be consuming +1 energy more than if you'd just did it manually. Same goes with Mass Distillery.
But yeah your other concerns are true. They do get better a bit in C4 onwards. The code and structure is "more organized", but the game is still mostly unplayable without guides. It is kinda hard to get a hang off event triggers. Basically:
- One Event Per Day: You can only talk to each captain once per day.
 
- Quest Assignment Event: Every Chapter, each Captain gives you Side Quests that basically progress their own character arcs.
 
- No Same Day Accomplishment: After a Quest Assignment Event, you cannot accomplish them on the same day they are given because of the One Event Per Day rule above.
 
- Filler Events: For the mean time that you do not have the resources to fulfill the quest, and if you have not spoken to the Captain that day, usually there will be some filler events once you actually talk to the Captain. In these events, the Captain will not give you more quests. Some of these Filler Events are really just flavor, other times it can impact the story.
 
- Quest Fulfillment Event: If you have not spoken to the Captain that day, and if you also have the required materials for the quest fulfillment, a quest fulfillment event will automatically occur when you talk with the captain. As per the game's script, this naturally takes higher priority over Filler Events. In these events, the Captain may give you another quest or just conclude their "main arc" for the Chapter. When that happens, filler events will still happen until the chapter runs out of them.
 
- The Time Stream: Having said all that, this "One Event Per Day" rule is mainly why people get confused with the triggers. Quest Events and Filler Events have to converge into one stream because only one of their events can occur in a day. These are two storylines trying to fight for one timeslot to occur per day. Therefore, to maximize action economy, I strongly recommend gathering the materials for quest fulfillment first BEFORE making rounds and talking to each of the Captains. That way, you can strategically prioritize Quest Fulfillment Events to occur over Filler Events. Basically, you'll be able to move through the important story quicker.
 
- Importance of Captains' Side Quests: Most of these side quests reward you with what you ultimately need for the Main Quests. In fact, in later chapters, the Main Quest itself is just to finish up all side quests. Hence, finishing Captains' Side Quests should be your priority. There's guides out there on which Captain you should prioritize, but you can get by without strictly following it.
 
On material carryover, I know it's upsetting at first, but in C3 onwards they introduce a mechanism to kinda allows this while keeping it balanced. Trust me, the game gets way too easy if all resources carryover across chapters. This is also why there is a One Event Per Day rule above. It's a balance thing. You'd be breezing through too quickly without these handicaps.
For combat, you just really have to find the "rhythm" of when the jotun makes its "major attack". I think for C2 and C3 they do it every 6 actions. For C4 onwards it's usually 4. What this means is that you basically need to make sure to use defend as much as possible every 6 (for C2 and C3) or 4 (for C4 onwards) turns, so that you can defend against heavy damage. You can do anything in between (better if you maximize synergies), but you'll be fine as long as you use defend every 6 or 4 attacks.