Read the (long) linked-to article from which the quote stems. Basically the point is that using violence to achieve a goal teaches the people involved that violence is an effective, legitimate way to achieve goals - and at some later point they will invariably have conflicting goals.

I'm not sure there's a useful distinction between those two options. Your future selves are part of the future world-states that it's exerting pressure on, and not exempt from that pressure.

I didn't read the quote as a blanket opposition to violence. It's a warning about one thing to consider before you choose violence.

I also didn't read the quote as only being about violence. It also makes a more general point about means and ends. When you're considering an action in pursuit of a goal, you should consider the action in its own right and try to predict where it is likely to lead. Don't settle on an action just because it seems to fit with the goal. This is especially relevant when you consider using violence, coercion, manipulation, or dishonesty for a noble purpose, but it also applies more generally.

Of course, sometimes one is prepared to find yourself in the kind of place it takes you to. The quote seems to already acknowledge this possibility.

That lesson is pretty frequently homeschooled, sad to say.