No. Not all college football players go to the NFL, not even all division 3 college football players go into the NFL
No, but most players do.
260 athletes have gone on to play professional football in the NFL
NFL players are not required to attend college. Still, it is quite difficult for a football player to gain the skills necessary to play in the NFL without playing college football. Still, a few European soccer players have been kickers in the NFL.
you draft them
College football season normal starts before the NFL season does. College is normally 3 weeks into their season before the pros start.
Approximately 7% of all college football players get drafted into the NFL.
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).