the U
college football is when you are in college and pro football is when you are out of college and also in pro football you get paid but not college football. you can get into pro by being a college player and getting drafted into pro.
SEC
Texas
Penn state
They are most likely to be 21-24
USC
Texas A&M
Most NFL teams will have open tryouts. Including players who were not drafted, players from semi-pro teams, free agents and players from other sports. Notable NFL players who never played college football are Antonio Gates (San Diego Tight End who played Basketball in college) and Carlton Hasselrig (Pittsburgh Linebacker who Wrestled in college).
Chicago Bears
no
Actually, unlike Baseball, where the pros accept players right out of highschool, the NFL is made-up of about 98% college football players in modern times. The chances of making it to the pros in football is very slim unless you play for a college team. There are some exceptions and most of those players have never become famous or household names. So, the answer you require would contain a list of thousands of players. Maybe 4,000+ names. Too many to list here.