Being a U.S. Marshall??? Info?

I have a close friend of mine who is very interested in becoming a U.S. Marshall. He wants to know everything about it and me being his closest friend helped him look up alot of info. But its alot of things the websites cant tell me. You know?? But he tore his ACL in his right knee and he's gaining his speed back would that hinder him from a U.S. Marshall career..... He also is very involved with family...Will there be time for a family?? Will his schedule be too busy for one?...What are the chances of becoming a U.S. Marshall?? Is it a good career to look into??? If you have any EXPERIENCE or have information to any of these questions...your help would be appreciated : )