I haven't read most of Civil War II (I didn't even care for the first one. Or the comic for that matter.), but obviously I know that Clint killed Bruce upon Bruce's request. But did the two of them have some kind of deep friendship? I'm not sure why he would ask Clint, wouldn't he ask someone like Rick Jones, Strange or his son or someone else? I'm not sure, am I wrong, or do the two of them have some type of close relationship? Thanks.
Probably because he knew that Hawkeye would actually do it. The others on your list would most probably not have it in them to take the life of Bruce Banner.