MRI's showing implants where the doctors said the person could not have survived having such an object inserted given the level of surgical knowledge on Earth. Another man in his 50's was recently complimented by his surgeon on the very excellent previous neck surgery. I had always heard that abductees had lower body temperatures than other people. So, I checked it out with several doctors' offices. I have heard of and seen various implants and scars.
Women are most prone to medical reproductive complications.
Radiation sickness has claimed the life of many household pets, especially dogs. But this is one of those lesser-known details. As for IQ increases, I am not aware of anyone having conducted any tests as you outlined. Unfortunately, people tend to categorize aliens based on appearance. There is a popular myth in this subject area that beautiful aliens are good and ugly aliens are bad.