Sesquame I'd be a lot more able to mess around and try to play the game properly if I at least had the ability to set up some start-of-chapter-4 saves where I don't need to worry about what I missed beforehand. What posts or resources should I be looking at to help me decide on the "correct" choices for a 2nd playthrough? Trying to read through the thread myself hasn't really helped since I'm not following a lot of the baked in assumptions when people discuss since I don't know Gawnfall inside and out and that apparently has a huge effect on what Ardford investments to make.
this is sadly impossibile, decision done in the first investement round can have an huge effect after, for example any early social gain is translate in less 100K+ investment to do to reach the social 40 treshold relevant in some chapter 4 event.
so thing like repair the bridge or fund the anti corruption campaign can be pivotal in the optimization (or not)
for making a good optimization you need to familiarize with the math inside the game, and the relevant threshold you must reach for gaining the important switches, the game works around this two thing, the hardest parts for the optimization are the first investment cycle and the chapters 3 and 4, starting with the Battle of Yhilin (BoY) the arclentian war (3AW) and the events in chapter 4 (succession crisis, erosia perlude, synod and erosia invasion)
the three chapter 3 trips (elven forest, zirantia and eustrin) are basicaly set in stone, the only decision you will make is lynine/orilise double choice, but for an optimizing point of view lynine then orilise is superior in nearly any aspect.
if you want an already done walkthrough you can take the one make by thosha (already linked above) or use my own (it's more a ultra condensed list of the choice that matters)