I'm glad you're enjoying it so far! Yes, we're slowly starting to work on a lore section that would explain magic more in detail alongside some other in-universe things. We're still very much in the early setup of the story and got a lot more to look forward to!
Yes, Thatcher's opinion of Tim does differ on the route you choose. Without spoiling much, you can notice that Thatcher definitely has some... baggage he's dealing with that affects his choices.