Some of the things you've mentioned are considered "old wives tales", there is no medical fact to them. I'm sorry you're being scared for no reason. Everything else you've mentioned is quite normal for a young man. There are books out there to help you learn more about slowing down and how to satisfy your wife. I do believe there is also a "mens health" forum here. You can click on "forums" at the top of the page and then scroll down.