- Companions can leave you if you piss them off sufficiently or make certain choices in their quests.
- Reputation with the four factions is important because it unlocks higher tiers of their units. It's generally a good idea to focus on one or two factions at maximum.
- That being said, apparently it's possible to go through the game without joining forces with anyone and the story accomodates for that; you also get a good amount of units from quests.
- Some quests will have consequences further down the line.
- You'll probably get enough experience to max or almost max two skill trees during a playthrough; you can also respec so you can't really mess up your build.