Assuming renewal, ATK1 is their ATK, and ATK2 is their MATK. I can't believe they still haven't fixed the documentation in a whole year.
INT and STR (and whatever else present in the formulas) affects the appropriate stats, this is the value of additional attack/magic attack on top of what comes from the monster's stats and level. Kinda like equip atk for a player. Min and Max values are also calculated, you can't set them.
Stat recalculation (after a script command sets them) was not working correctly, so if you're trying to do that, you'll have to fix the source first. Most importantly, script commands to read and write the stats don't set the numbers you expect them to and/or set something that makes no sense (for example yes, you can set max atk from script but then next time it's calculated the value will be replaced so that's pointless. )