Dice rolls: these should have the bonus/penalty modifier added to the value of the dice rather than subtracted to the target. Apparently this is not just a subjective matter but contradicts the D&D rules that rolling a 1 is an automatic fail no matter what.
When you said an automatic 1 means a fail on D&D, do you know that is not in the rules right? It is a house rule. Unless it is during combat a 1 can still mean success if you have enough bonus added to it.