I need to verify how good (or bad) my understanding of to-hit-and-crit rolls is, so can some kind person please verify, clarify or falsify this:

1) To hit, you roll 1d20+ (your attack modifiers) - (target AC) if the net result is greater than a 1, you always hit.

2) If you hit above AND your d20 roll was better than the effective critical threat range for your weapon, you roll to confirm a crit, which is basically the hit roll, modified by +seeker bonus - if the second rollis ahit, you get critical hit.

3) If you miss on 1, but d20 >10, you get a grazing hit (weapon hit di(c)e only, no effects, etc.)

It's based on this, and the way that hit and AC scale with level that neither players nor monsters miss much above a certain level. Itseeems like it's somwhere around level 12-16 that happens for player armour.

But when does it happen against monsters? I'm guessing at an attack modifier around 30-ish (based on a SWAG that most monsters have ACs around 30), but is that right?

Thanks in advance!