. Change offsides to an offside line like it is in ice hockey. No offensive player can enter the offensive zone until the ball has crossed the line. After that, offensive players can be anywhere within the offensive zone regardless of where the ball or defensive players are.
That might be worth trying. But I'm going to guess that it wouldn't work.
2. Stealing from hockey once again, if someone is actively playing the ball you can hit them with your body. No elbows or blows with the feet, but a good body check is legal.
No. It would deprive the game of much of the individual skill that makes it so enjoyable to watch. If you did that then how could someone be a genius with the ball at his feet? He could just be body-checked, and that would be the end of it.
3. No throw in. Free kicks from the side line.
Why? I mean, I can't see an argument against that, but how would it improve the game?