actually two, things i am seeing more and more and not sure what the rules are because when i played organized basketball they were not as common.

one, if you're denying the ball to an offensive player (not making contact with him but putting an arm in front of him to disrupt a potential pass to him), can he just push it out of the way? guarding guys in the post and getting an arm in front of them (again no contact) some will push it down with their left arm or sometimes both arms. that doesn't seem legal but i don't know what the rule is.

the other one is on screens. you're going to set a screen and you're already set, can the defender you're screen hand check you or push off you for leverage? some of these guys throw a hard hand check into you or, let's say your man rejects the screen and goes the other way, they will extend an arm and push off to get a stronger step in the direction of the ball handler.

are these things illegal or just annoying AF?