I think it claims to be Heavy-Duty because it has a fire rating of 435°F when others are rated at 320°F. Also this duct claims to meets UL requirements.
That's a question for manufacture's customer service..
Mine did not.
It is flexible and should be okay if your access hole is slightly wider then 4 inches and do not crush th pipe.
Do you have long then 8 ft. Thank you
Should be okay!
Should as it is very strong, but they could be using the vent exit flap to enter. That could be the problem rather than the duct work.
it only expands to about 5 feet maximum
It cuts nicely with heavy scissors.