In American Football one tackles a player. In Association Football (soccer) one tackles the ball.
Solo Tackles
Linebacker.
4
yes
it's between the two defensive tackles
Dallas Cowboy Free Safety Barry Church has the most tackles in the league for a defensive back thru week 16 in the 2013 season. He has 127 combines tackles, with 100 solo tackles and 27 assists.
The guards. Then, the tackles. Then, receivers.
Tosh-0 - 2009 Football Player Tackles His Teammate 2-4 was released on: USA: 3 February 2010
American football tackles can be seen online for free at Youtube. Local television stations will broadcast games for free as well all season long, so just tune in.
yes
Helmet-To-Helmet are not allowed. If that's what you were asking.