Hey thanks so much for the note! Glad you are enjoying it.
1) In White Box, it's all d6 dmg. You can alter monster strength if you want by doing d6-1 or d6+1, but typically all monsters all d6 dmg
2) It's your game. Typically the monsters don't level up. But seeing as a GM isn't creating the encounter you can either, just always use Tier 2 or make the baddies have more HP or variable damage (d8, d10) to simulate a harder level.
Hope this helped!
Cheers!
PR