Your bottle of Kombucha will contain culture sediment, which can look stringy or form a film on top of the drink (baby SCOBY). This is totally normal, safe to drink, and shows the Kombucha is still living and active.
Yes, it is supposed to be lightly effervescent. This is 100% naturally occurring during the second fermentation. The amount of fizz varies from batch to batch and flavor to flavor. The health benefits are still present in Amada’s Kombucha even if the fizz is not.