Personal Foul- an illegal personal contact made by any player to an opposing player. In can occur during a defensive possesion(blocking, shooting) and offensive possesion (charging).
1). Blocking- is illegal contact which impedes the progress of an opponent.
2). Shooting- an illegal contact made with an offensive player during a shot.
3). Charging- illegal contact by pushing or moving into another player's torso.
In a game a team usually has limited number of personal "fouls to give". (im not sure exactly how many) This prevents teams from abusing the use of fouls during late game situation. Team fouls are the total number of personal fouls all players from a single team committed in a game, if the number exceeded the "fouls to give" limit, then the opposing team will get to the freethrow line after every foul committed.
Freethrows are awarded as a penalty for being fouled during an act of shooting(shooting foul), and the amount of freethrows depends on the value of the shot taken, 3 for beyond the three pt line, an two within it. If the offensive player made the shoot during a foul, then he is awarded 1 bonus freethrow. If a team, however exceeded the "foul limit", then every personal foul committed by that team will result to 2 freethrows. Freethrows are also awarded to technical fouls (1 shot) and flagrant fouls (1 shot + possession).
Committing a travel will only result into a turnover, transfer of possesion to the other team. Also there is no 3 second foul.. I think what you mean is the 3 second violation. It is committed if an offensive player stays for 3 second in the shaded lane, or a defensive player is guarding an opponent without the ball for 3 seconds.