What should the pavement temperature be to crack fill?

You can fill cracks as long as the pavement is 40°F or warmer. If it is colder but you need to fill cracks, use a heat lance to heat the pavement up before you apply it.

What temperature does the crack filler need to be to flow?

The best temperature for heating your material is 380-400°F (193-204°C); any higher than 400°F may severely damage the product. Prolonged heating can also damage the product - heat it only when you are ready to apply it.

When melting the rubberized crack filler, does the whole block with plastic wrapper go into the melter kettle?

Yes, you can put the whole block into the melter kettle along with the plastic cling film. Don't worry because including and melting the plastic film is 100% safe. Plus, it will not affect the adhesion or the performance of the rubberized crack filler.