I'm so touched you're finding magic in my little game <3
3: it's a "high trust" factor, yes! there's no explicit damage standard for spells like Acid Arrow or Fireball (though Magic Missile always deals 4)
at my table I run magic damage based a lot on context (though I don't expect everyone would run it that way): sometimes it's 4d4 Breach 2, sometimes 1d4+4 until they stop the burning, etc. Often I'll just ask the caster what feels right to them, but my considerations tend to include questions like "is the target armored, dodging, covered in oil, made of paper? what's the minimum damage this should deal? should there even be a damage roll? do I want this to maybe cause injury?" and so on :)
