1/4 " was to wide for our door. This was 3/16 " and fit perfectly.
Measure track on bottom that seal fits in there are a couple different sizes
Depending on how old your garage floor is, I would contact the contractor who placed the concrete floor. This seal will not solve the problem of a space that large on the bottom of the door.
The ends might be pinched a little to keep the gasket from sliding out. Try a flat blade screwdriver to spread the channel.
No. Just the bottom seal. Note: It is important to get the correct "lip" at both ends of the curved (U shaped) seal. The one I received was thicker than required, which made it more difficult to install. You probably should get the thinnest that they make.
Yes, it was 20 feet.
It is at least 4 inches wide to accommodate different size doors
I only saw black on the webpage.