The comparison between NEO and KBO is good one.
The redishness of some of the KBO has been something I've wondered about. Are they really this red and what is significant regarding life or precusors of life? Why are these distant objects red and why aren't any NEOs red- or are any NEOs this color?
The migration of KBO's (or even objects further out) to the inner solar system, is a major factor in understanding the NEO population [over millions of years NEOs would cleared from their orbit]. "Exactly" how long this takes and various mechanism responsible for replenishing the population could be a key factors in determining a more precise impact risk assessment. In other words, is the NEO population largely from the Main belt or are comets a major source (and is current NEO population high, low, or about the average it's been for the last billion years) . If comets are a significant source is it a random steady stream or are there cyclical events which trigger a large flux of comets- and/or a large comet ever once in a while break up and make lots of comets (similar to Linear but much larger). [Linear: http://www.solarviews.com/eng/linear.htm ]