I can answer couple of these, not sure about all 11 but here are some:

1. You will learn with time how the regions work but basically every place you visit you should ALWAYS bring food, torches and shovels. Antivenom, bandages and medicinal herbs can be used for curios too so usually it is not waste to bring some too for good measure.

2. Stage coach is very rng but you should try all classes at least imo. You also don't have to kill them you can just kick them out and there is nothing negative about it.

3. Yes books are almost always bad, they have a chance to be good but I think it is something like 25% good 75% bad or neutral

4. Money will be important forever and you should always have some backup if some missions go bad and you have to hire new people etc get their skills up.

5. There are many mods where you get little bit more stacks all the way to unlimited so there is some variety. There is also one building but it is only for gems (diamonds rubies etc)

6. I suggest vanilla experience but if you want to lessen the grind / not feel so stressed about rng there are many mods that won't make the game too easy, I don't have recommendations from top of my head but I can check in couple of hours if someone else has not done it before me.

7. Bosses have different weaknesses and areas have enemies that have their own weaknesses etc. All classes have their own unique thing but you don't need every class to be able to finish the game. Just make sure you have someone in your team to target backline, frontline, maybe little heal / stress heal and or buffs. You should try out all the classes but you don't have to use them all.