I'm not a native speaker. Forgive me if it's obvious and I just don't understand.

With the new text in the tractor rule, "this way" refers to a previous movement. Is the reference "to move through or overlap an obstacle" from the previous sentence meant or does it refer to the above "Perform a barrel roll" and "Perform a boost"?
Could mean that the 90° turn is only a option if an obstacle is involved.

No, you get to rotate whenever you were moved in the way that the two bullet points described: forward or sideways.

Don't worry, its not super clear how they have written it, but i think most of us get what they are going for by it.

The basics of it is, being tractored alone isnt enough to allow you to rotate, your opponent also has to opt to reposition you using one of the two bullet point methods.