Unfortunately color cannot be specified when ordering online.
No it does not stretch. It is the same consistency as clothesline rope.
Yes it might if you got a larger size - this one is 5/32 which is very narrow. You'd need something much bigger to be able to handle the movement unless you attached some kind of weight.
This would nicely for kite flying if it's a larger high quality kite. It is light enough for most kites that have legit size so it will weigh more than the rope.
I bought this with the understanding that it was a 4 pack of those 4 colors like the image implies. Was super disappointed to get to the store to pick it up to find that they choose randomly what color they are going to send / package up for you. And it is only 1 winder not 4. It was easier to just suit up in the PPE and head into the store to find what I needed.