I'm pretty sure those are the basics. I THINK that for the most difficult quotes there are 10 points deducted for each minute it takes to solve....so if you solve it in less than 60 seconds there are fewer points deducted.
What I'm not sure about is if this rule holds true for each level, but I don't think it does. I THINK that if it's an average quote, it takes longer than 1 minute for 10 points to be deducted, and for an easy quote it is still more. But I have no real way to know this, except just a "gut feeling". It would take someone far wiser than myself to develop an algorithm to figure it out.