Is a 0 on a "stress die (no botch)" roll still counted as 0 or does it count as 10 (like Quality Dice in 4th)?
It is a stress die in all ways except that there is no chance of botching (ie instead of rolling botch dice, you just treat it as if botch dice were not 0s)
0 is 0 and 1 doubles which is what makes it different than simple die (1-10).
Welcome to the game!
That's covered pretty clearly on page 6, under "Stress Die" - (re-)read the third paragraph:"...On the first roll, zero counts as zero... If you roll no zeroes on the botch dice, the die roll is simply zero.
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(& par 5) ...If you roll a zero but do not botch, the total is calculated as normal, adding zero from the die roll."No one of the rules is very complicated, but there can be a lot of them to find and then remember, no doubt. Any other questions, plenty of people who can answer, don't be shy!
I know about normal Stress Die rolls, I was just wondering about the special occasions (like Twilight Avoidance), where it practically seemed like the Quality Dice of yore. 
But obviously, it's different.