Some areas of the country do throw the weight in youth competitions. If you or one of your athletes is scheduled to throw in a youth meet, you will need to contact the meet director and check what size weight they will be using for the age group.
In the sense of performing as designed, most radar detectors do detect the presence of police radar in the immediate vicinity of a speeding vehicle. Whether or not that information will actually prevent a driver from receiving a speeding ticket remains to be seen, however.
An x-band radar has a low-frequency and a high out-put, making it relatively easy to detect from 2 to 4 miles away. However, devices other than police radars generate x-band signals, including garage door openers and microwave towers. K-band radar is most commonly used by police, and has a small wavelength.