In my experience, people tend to worry more about their protein intake than they really need to, especially athletes. The typical adult gets more protein than they actually require. This is true for most athletes, too. You can get general information about protein, including dietary requirements, here.
You can learn more about nutrition for athletic performance from the American College of Sports Medicine here and about protein specifically in this article in Physician and Sportsmedicine. These are both pretty scientific, but you can find good, low-sci information here.
Vegetarian and vegan diets are becoming more popular. The restrictive nature of vegan diets, in particular, is associated with both health benefits and potential health concerns. However, through careful meal planning, both vegetarian and vegan diets are healthy, even for athletes.