Kicking is a violation whether it is done by a defensive player or an offensive player. The kick needs to be intentional. The foot needs to be off the floor.
No. It is not a violation if the contact with any part of the foot or leg was accidental. If it was intentional then the player is guilty of kicking the ball.
You can't, not only is it almost physically impossible to play with your feet, it is illegal for the ball to touch your feet in a basketball game, it's called kicking and is a violation.
The players.
Foul and violation.
Yes
There are many like the shotclock violation, 8second rule
yes
Travel
Yes
There is no violation. It is the same as a pass
Yes. It is a walk