How much can ball handler use his arm?

[potato]

It's pretty common to use Ball Handlers using their non handling hand to protect the ball, create space and more often using it to lock defenders behind them when they overtake them. However is there a line between what is legal and what is not?

For example is it legal to dribble side by side with the defender with your non-handling arm stretching outwards to create space between you and the defender (without overtaking the defender).

Also is it legal to use your arm/hand to press on a defenders upper leg/waist so the defender can't even move to block your path? Usually this happens when the ball handler is facing his back on the defender. Most of the time i see the handler just extend his arm so he can get a path but today i saw some guys pressing on the defenders upper leg that he can't even move sideway to defend.

It would be an offensive if the action is pretty obvious like pushing etc but using the arm to block/prevent defender's movement is there a line between legal & illegal?