Crowded
The comparative form of "crowded" is "more crowded."
Yes. "Crowded" can be a verb (as in "People crowded the stadium") or an adjective. (as in "The stadium was crowded because of all the people.")
Yes. Very crowded.
Its VERY crowded
The room is crowded.
Part of it would be the rotation of the earth, but the biggest reason is Nashville's airport is a lot less crowded than Seattle's so it's quicker to get on the ground once you're in their pattern.
Diffusion
That is the correct spelling of crowded (congested, cramped).
Is coach too crowded
Crowded House was created in 1985.
Crowded House ended in 1996.