just what i needed, thanks

Are the mounting brackets sold separately for those who already own a telescoping ladder?

What is the smallest opening this can work with?

The animation shows the ladder extending downward, but how is that actually accomplished mechanically? I own a telescopic ladder, and it extends upward by having to release each rung individually, by hand of course. I would imagine this attic ladder works similarly, but instead of extending upward as with my ladder it extends downward.

How much