No, not all eggs dimple. I've had plenty go full term without dimpling. Temps do have an effect on hatch dates but I'm not sure how much. I've had eggs hatch anywhere between 50 days and 70. The books all say that they hatch at 60 days but ball pythons don't read very well. MOST of mine will hatch around 60 days give or take but it's certainly not a hard and fast rule.
Sorry to hear about your lost eggs, for the one that did come out if it still has it's yolk the best thing to do is to set it up on very wet paper towels and allow it to absorb more yolk if it can. I would not remove the yolk sack but let it fall off naturally. Sounds like it may have been a bit premature. Did you cut the eggs?