It is built as a vacuum flask: two steel walls with the air removed from the space between them. Heat travels through solids and gases, so removing the gas removes most of the routes it could take.

No. The design is on the outside of the outer wall, so it never contacts the liquid. What wears it is abrasion from bags, cup holders and counters rather than anything you drink.

Treat that as a risk rather than a convenience. Sustained heat and detergent are hard on an exterior print and on some seals. Hand washing with warm water and a soft cloth is much kinder to the design.

No. The body is steel. Never put one in a microwave.

Because the outer wall stays near room temperature, so no condensation forms. The same mechanism keeps the outside comfortable to hold when the contents are hot.

Yes. Damage that breaks the seal between the two walls destroys the insulation permanently, even though the cup appears to work normally.

Not necessarily. Large tumblers often will not fit a car cup holder or a bag pocket, which is where most of them live. Check the base diameter as well as the capacity.