How long will it stay within a specific temperature range?

That depends on the model, ambient temperatures, and desired range. Hours listed in literature are results of testing following ISTA 7D procedures. Testing involved a 24-hour cycle of summer (71.5°-95°F) and winter (14°-64.4°F) temperature profiles. Individual results may vary.

Is there an expiration date?

No. With some general care and precautions, many years. The cases can take some wear and tear. The VIP loses only 5% effectiveness over 5 years. The PCM panels are indefinite.

Is there a warranty?

A 1-year warranty. Which can be found here: